454 SM465 4.10 vs 3.73 vs 3.54

[KnockingDiesel]

I’m in the process of converting my C30 to four-wheel-drive, and will have to re gear the axles.
The truck will pull our 5k-6k lbs boat 3-4 hours to the lake and used to hunt in the fall/winter. as far as highway driving 3.54 seems like the way to go but if I have to drop to 3rd at 62 mph to keep the load moving, I may sacrifice cruising speed. Fuel consumption isn’t really the concern it’s more engine longevity and comfort. Right now at 65mph-70mph engine feels like it’s being pushed. Most loads will be the the boat or heavier in town loads up to 10,000 lbs. I have pulled 10k+ in town landscaping my yard and never felt under powered.

3.54 75 mph @ 2825 rpm, 65 mph @ 2450 rpm and 62 mph @ 4000 rpm in 3rd gear.
3.73 75 mph @ 3000 rpm, 65 mph @ 2600 rpm and 59 mph @ 4000 rpm in 3rd gear.
4.10 75 mph @ 3300 rpm, 65 mph @ 2850 rpm and 54 mph @ 4000 rpm in 3rd gear.

I’m trying to use this truck as often as possible for as many uses as I can. I have diesel one ton for really heavy loads so this truck will be used in a personal or recreational setting but I’d like to be able to use it in a pinch to pull my heavier loads if possible.

I have looked into an nv4500 or gear vendors, which would be nice but I have to re-gear an axle and rebuild both axles anyway. and the cost for either od option is pretty high.


Any thought, opinions or suggestion are greatly appreciated.

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[SquareRoot]

So what gears are in it now?

 

[Strick]

I'd go 4.10 and drive it. We had a 74 Crew years back with that gearing and it didn't matter if we had 100 gallons of fuel plus all the equipment as well as the trailer loaded, it was 8mpg empty or loaded.

Strickland

 

[KnockingDiesel]

I think it currently has 4.56 possibly 4.10 I have open the cover to see, the tach is a little bouncy.

 

[SquareRoot]

I think it currently has 4.56 possibly 4.10 I have open the cover to see, the tach is a little bouncy.

Lesson #1. Garbage in=Garbage out.
1. You say "if I have to drop to 3rd"... Are we left to assume it currently has a 4 speed?
2. You say K10/350 in your signature but the photo is a C30 as you reference in your post. Please clarify were talking about the same truck.
3. Is the truck in question a gas or diesel engine?
4. You say "Fuel consumption isn’t really the concern it’s more engine longevity and comfort".
Lets chew on number 4 for a minute. If you're converting that C30 to 4WD then money isn't an issue as is "fuel consumption" as you say. So we can toss those variables out of the equation and focus on your priority which is "longevity and comfort". The single most effective part you need for those is an Overdrive. A slower turning engine will live longer, produce less noise and vibration which adds too your "comfort" level. Therefore you have a choice depending on whether you currently have a manual or auto trans. If it's an auto, you should probably just drop a 4L80 in it and be done. Remember, you indirectly inferred cost is not a concern. Since we have to assume it might be a 4 speed manual trans (because you left out a LOT of details) there is another way to meet your goal. Either take advantage of the factory pedal assembly (assuming it's currently a manual trans) and put a NV4500 in it (again-cost is not a concern-right?) or a Gear Vendors OD. With ANY of these options you will have 5 gears, and you would have no reason to change gears in the axle.
See how this all works together? It's a domino effect that will take you straight down the Rabbit Hole, so put your seatbelt on and enjoy the ride!

 

[KnockingDiesel]

Lesson #1. Garbage in=Garbage out.
1. You say "if I have to drop to 3rd"... Are we left to assume it currently has a 4 speed?
2. You say K10/350 in your signature but the photo is a C30 as you reference in your post. Please clarify were talking about the same truck.
3. Is the truck in question a gas or diesel engine?
4. You say "Fuel consumption isn’t really the concern it’s more engine longevity and comfort".
Lets chew on number 4 for a minute. If you're converting that C30 to 4WD then money isn't an issue as is "fuel consumption" as you say. So we can toss those variables out of the equation and focus on your priority which is "longevity and comfort". The single most effective part you need for those is an Overdrive. A slower turning engine will live longer, produce less noise and vibration which adds too your "comfort" level. Therefore you have a choice depending on whether you currently have a manual or auto trans. If it's an auto, you should probably just drop a 4L80 in it and be done. Remember, you indirectly inferred cost is not a concern. Since we have to assume it might be a 4 speed manual trans (because you left out a LOT of details) there is another way to meet your goal. Either take advantage of the factory pedal assembly (assuming it's currently a manual trans) and put a NV4500 in it (again-cost is not a concern-right?) or a Gear Vendors OD. With ANY of these options you will have 5 gears, and you would have no reason to change gears in the axle.
See how this all works together? It's a domino effect that will take you straight down the Rabbit Hole, so put your seatbelt on and enjoy the ride!

I fixed the signature. The truck is a 1982 454 sm465 c35 that I am converting to 4x4 I have a K30 frame, sm465 trans, 205 t-case and Dana 60 front.

The reason for re gearing is that Dana 60 steer axle is 3.73 ratio and the dually rear end is 4.10 or 4.56 so I was trying to compromise since I have to rebuild and re gear the truck any way. But I feel like the gears/powerband will be wrong for towing or highway driving unloaded or both if I compromise here.

The more I look at the numbers the more appealing the gear vendors becomes.

I considered nv4500 but none locally except 2wd every now and then. By the time I get the bell housing to work with the z bar, tail housing and out put shaft I’m over $3k. Rebuilt nv4500 4wd are $2500 plus bell housing and shipping. So that’s kind of a wash between the nv4500 options.

I looked into the TR4050 but that’s closer to $5k all said and done and the 4l80 swap is about $4k-$5k. And I don’t really want an automatic.

While I’m not made of money I believe in do it once do it right. So $3200 for a gear vendors seems like a decent deal for a bolt on all inclusive option.

I think the ideal setup for what I want is a 4.10 gear and gear vendors. I think 2500 rpm would be a good cruising speed.

Also if I could get the GV to work from a shifter mounted switch, like the old Eaton 2 speed diffs, that would just be the cherry on top.

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[SquareRoot]

With that info I would hope the current gears in the rear are 4:56 and entertain the GV behind the 465 trans. I would never use a GV behind an auto because you still have a non-lockup convertor to worry about. In that case, just put in a 4l80. Behind a manual is a different story. In fact my dad had that same setup in his 82 K30 diesel and he towed a horse trailer full of construction equipment all over the country. I researched all of this to death when I converted my 85 K20 from auto to manual. I hate automatics in general so the NV4500 was a no-brainer for me. I have two of them, one I just completely rebuilt. Between the trans, AA bellhousing and clutch I'm in about $2500. I have 1 ton axles with 4:56 and they are great all around with 32 inch tires. I get decent mileage, avg 15 open road (Edelbrock EFI) and love driving the truck! Don't forget the cost of driveline mods with the GV, those can add up quickly.

 

[KnockingDiesel]

Also if

With that info I would hope the current gears in the rear are 4:56 and entertain the GV behind the 465 trans. I would never use a GV behind an auto because you still have a non-lockup convertor to worry about. In that case, just put in a 4l80. Behind a manual is a different story. In fact my dad had that same setup in his 82 K30 diesel and he towed a horse trailer full of construction equipment all over the country. I researched all of this to death when I converted my 85 K20 from auto to manual. I hate automatics in general so the NV4500 was a no-brainer for me. I have two of them, one I just completely rebuilt. Between the trans, AA bellhousing and clutch I'm in about $2500. I have 1 ton axles with 4:56 and they are great all around with 32 inch tires. I get decent mileage, avg 15 open road (Edelbrock EFI) and love driving the truck! Don't forget the cost of driveline mods with the GV, those can add up quickly.

In my situation looks like GV is the way to go, I’ll match the front axle to the current rear gear and install the gear vendors unit. unless you would you sell one of your nv4500?id regear both to 4.56 if I had the nv4500 as it’s od is a bit taller. Do you need an adapter to from the 4500 to the 205? Or will the 465 to 205 work?

 

[SquareRoot]

You need to verify what gears are in the rear. There's a thing called "Carrier Break" and I think it's between 4:10 and 4:56. You cannot change ratios higher or lower without changing the gear carrier. I put the , original axle in with the 4:10 gears recently while I removed the locker in the 4:56 axle. I definitely prefer the 4:56 over the 4:10 with the OD. Unless you have the hard to find and expensive late version (6 bolt round pattern) 205 case you will need an adapter for the nv4500 to 205 case. Your 465 should bolt up if the splines on the input shaft are the same. If not, a new shaft is inexpensive.

 

[KnockingDiesel]

You need to verify what gears are in the rear. There's a thing called "Carrier Break" and I think it's between 4:10 and 4:56. You cannot change ratios higher or lower without changing the gear carrier. I put the , original axle in with the 4:10 gears recently while I removed the locker in the 4:56 axle. I definitely prefer the 4:56 over the 4:10 with the OD. Unless you have the hard to find and expensive late version (6 bolt round pattern) 205 case you will need an adapter for the nv4500 to 205 case. Your 465 should bolt up if the splines on the input shaft are the same. If not, a new shaft is inexpensive.

That’s a nice setup but too many variables for me, having no experience with this swap, I’d rather do the GV since there is less chance of me buying all the wrong parts,


I appreciate all of your information

 

[Bextreme04]

That’s a nice setup but too many variables for me, having no experience with this swap, I’d rather do the GV since there is less chance of me buying all the wrong parts,


I appreciate all of your information

This is misleading. You are just as likely to mess it up with the gearvendors. It will change the position of things and will need all kinds of adjustment and compatibility considerations.

If you want simple and functional, just use the K30 drivetrain and regear the rear end to 3.73 to match the new front diff. Don't worry about the carrier break and just get yourself a yukon duragrip carrier to match your new gears. That way you have a reliable limited slip and no compatibility issues. The 465 has a low enough first that you should be fine with that 454 towing and still have a reasonable rpm at highway speeds. The 3.73 was usually the default gear for a 454 equipped truck.

 

[SquareRoot]

This is misleading. You are just as likely to mess it up with the gearvendors. It will change the position of things and will need all kinds of adjustment and compatibility considerations.

If you want simple and functional, just use the K30 drivetrain and regear the rear end to 3.73 to match the new front diff. Don't worry about the carrier break and just get yourself a yukon duragrip carrier to match your new gears. That way you have a reliable limited slip and no compatibility issues. The 465 has a low enough first that you should be fine with that 454 towing and still have a reasonable rpm at highway speeds. The 3.73 was usually the default gear for a 454 equipped truck.

Good point. The other consideration is that everything that's not new has about a 99% chance of needing rebuilt anyway. Bearings and seals don't last forever. That cost adds up fast.

 

[mcarlo86]

This is misleading. You are just as likely to mess it up with the gearvendors. It will change the position of things and will need all kinds of adjustment and compatibility considerations.

If you want simple and functional, just use the K30 drivetrain and regear the rear end to 3.73 to match the new front diff. Don't worry about the carrier break and just get yourself a yukon duragrip carrier to match your new gears. That way you have a reliable limited slip and no compatibility issues. The 465 has a low enough first that you should be fine with that 454 towing and still have a reasonable rpm at highway speeds. The 3.73 was usually the default gear for a 454 equipped truck.

I agree with this. This would be the simplest and most straight-forward option.

 

[Shorty81]

I have K20, 496BB, SM465, 3:73, 32" tires. No complaints here. 2500 RPM=65 mph. Plenty of power to pull. I have no need to speed up and down the roads....life goes too fast as it is and don't want to spill my beer!!

 

[KnockingDiesel]

This is misleading. You are just as likely to mess it up with the gearvendors. It will change the position of things and will need all kinds of adjustment and compatibility considerations.

If you want simple and functional, just use the K30 drivetrain and regear the rear end to 3.73 to match the new front diff. Don't worry about the carrier break and just get yourself a yukon duragrip carrier to match your new gears. That way you have a reliable limited slip and no compatibility issues. The 465 has a low enough first that you should be fine with that 454 towing and still have a reasonable rpm at highway speeds. The 3.73 was usually the default gear for a 454 equipped truck.

That was my initial consideration, since I’m pretty much building the truck frame off and want use it often. I am going to replace all bearings and reseal both axles at which point the labor would be an extra hundred dollars plus the cost for gears.

Since that will get done no matter what I wanted 3.54 to get the rpm’s where I wanted. 3.73 is still revving high. With the GV I can have 4.10 which is excellent for towing and be at 2500 rpm @75 mph.

I do not like the engine turning 2800-3000 for several hours.

Main focus is longevity, then comfort. If a 454 can spin 3000 rpm from Albuquerque to Denver or Phoenix without sever life reduction then I’ll add more insulation to the firewall and floors, skip headers and keep manifolds, etc. to reduce cabin noise.

I’m trying to lay out a plan so I don’t spend cash aimlessly.

My only concern is the truck will need to cruise @75 mph and not kill itself while still being able to tow. I know I can buy a newer truck ready to go probably cheaper but I want to build this one (sentimental reasons).

I really appreciate all your replies and input keep it coming.

The plan is over the next year to finish the truck. I’m not “upgrading” anything other than OD/re-gear and maybe cross over steering. I’ll replace all bushings, blast and paint axles, frame and springs. It won’t be a show stopping resto mod, just what it would/should have left the factory like. The only outsourcing would be re-gear. Everything thing else I can do body/mechanical/electrical.

The truck has no rust and is very straight, I’m replacing the harness so everything is coming off the firewall any way so I’ll be doing a color change Or going back to og blue.

So if necessary I’m willing to wait for nv4500 or spring for a GV if that’s the better option.

My only concern is that I can make long trips in my K30 with same reliability as my 7.3 Powerstroke.