Help me build my truck - What should I do?

[Hunter79764]

I had a similar thread before but it was much more open ended, and I did not have a budget or a time laid out at that point. Now I'm lining up what work I'm going to do on my 87 K20 Suburban. overall, it is decent driver quality, 120k original miles, every panel is dented and has been painted by previous owner in bedliner (which is fine, I like the Mad Max look for it). Overall goal is to have a rig that I can take camping with my boys, probably long drives to get to the mountains and backcountry driving from there (I live in Dallas area, planned areas I want to be able to drive to are Denver area for elk hunting and Moab for fun). Currently has a TBI 5.7 that works ok and a TH400/NP208 that should be mostly fine but need some work right now. Stock suspension on 265/70R16 All Terrain TA's that are ok for another year or two max, 3.73 Dana 44 up front and 9.5SF 14 bolt out back.

I've got some plans/ideas that are conveniently all "About $2 grand", but sadly, I can't afford all of them in one go-round. That's where you fine folk of the internet get to help

Potential Budget Lines:
#1 8.1 Swap - This one isn't actually up for debate, I have the engine already and most of the accessories. I'm going to say the cost to complete is a $2k bucket, but I might be less than that with the parts I already have on hand.
#2 Manual Swap - This truck just kinda feels like it needs a stickshift. Plan would be SM465 and NP205 from a K30 most likely. Up for debate on hydraulic vs mechanical clutch, I want it as simple as possible, and right now I'm pissed at "fluids" in general on my DD cars, so that leans me toward mechanical clutch but I'm not dogmatic on that.
#3 Axle Swap - Dana 60 up front, 14BFF out back. This might push over $2k since that's what I'm finding the axle for, but close enough and fairly self explanatory. 14 BFF might happen no matter what.
#4 Suspension Lift/Upgrade - Based on tire choice, ~4" lift via ORD shackle flip in the rear and either a set of Softride 4" lift up front or a homemade B52 with 37's and fender trimming, or similar 2" for 35's with trimming. New shocks (Bilstein maybe? TBD), maybe stretch to get crossover steering, although that would push me over that magical $2k number, I'm sure.
#5 Humvee wheels/tires - I love the looks of these and it is a cheap way to get into 37's, but the limitations of 16.5's and the heavy weight is not lost on me.
#6 35's for my stock 16's - Yep, just what it sounds like
#7 37's on craigslist 17's - should be able to get used wheel/tire set for 37's if I go to 17" rims, looks like Dodge trucks with takeoff 17s are popular around here.
#8 Custom Trailer - Buy/make a truck bed trailer from a long bed square, paint to match the black bedliner of my Suburban, and mount similar wheels/tires and probably identical axle for spare parts reasons?
#9 Deck Out the Exterior - Swing away tire carrier, mount some lights, upgrade my roof platform, get a winch for the front, fabricate a beefy back bumper, etc.
#10 Deck Out the Interior - Dynamat the interior, recover the seats, upgrade the stereo, install AC
#11 Add Overdrive - doing a 4L80E or an NV4500, either one would probably cost about the same. Doing the NV4500 is probably on top of the manual swap cost above, i.e. probably $4k to get a manual w/ overdrive. Long highway trips would definitely benefit, but honestly, the MPG's will take 10 years to pay for itself at 2500 miles per year, I'm guessing.
#12 NP203/205 doubler - Extra low gear, probably most useful if I keep 3.73s and 37" tires, but I think big block torque helps make the most of taller gearing anyway.

I'm getting lined up to start work over the winter, hoping to have it driving with the 8.1 by late spring, so parts gathering and planning while I'm getting house projects complete before then.

 

[Grit dog]

Long road trips in a square with no OD (hopefully has AC and cruise with the 8.1 swap) feeding a 8.1?
How about option 12? Find a nice used GMT400/800 3/4T 4x4 burb. Slap a lift and some big tires on it and let er rip.

 

[Hunter79764]

Long road trips in a square with no OD (hopefully has AC and cruise with the 8.1 swap) feeding a 8.1?
How about option 12? Find a nice used GMT400/800 3/4T 4x4 burb. Slap a lift and some big tires on it and let er rip.

These trips will be the "Character Building" type trips with my boys... I've done worse myself, and they are getting to the age when being tough is cool, I'd enjoy out-toughing them Gas costs will suck, absolutely. I already have an 8.1 in my motorhome, so 6-7 mpg is well understood.

 

[goldpack]

bigger brakes than 16" rims permit.

 

[nvrenuf]

Just my .02 on a few things....

#2 Manual Swap - I wouldn't stress about getting one from a K30. These combos are basically the same for 10/20/30 series trucks with the exception of yokes. The vast majority will be 10 spline and you'll need to check the trans tailshaft for spline wear but these are cheaper than the later 32 spline units which bring more money. '85+ combos use the short foot, round pattern adapter and are typically a good bit more expensive than the older 10 spline units. 10 spline units can be converted to 32 spline for probably less than $500 if you just want the bigger spline count.

#4 Suspension Lift/Upgrade - be careful what you ask for with 52's, that can be a deep rabbit hole of long travel driveshafts, steering mods, etc. I have 2" lift 52's on my Blazer (dedicated wheeler) and it rides like a boat, lots of body roll and rocking front to back. It's not unstreetable by any means but I don't think I'd travel in it. A quality off the shelf kit can be made to flex a little more than average and ride well.

Doubler: I have one (ORD) and I've very happy with it, it's very beefy so I have zero concerns about breakage. That said, if I were to buy something today I'd probably get a Magnum instead. Underdrive boxes like the Magnum have greater versatility because of more ratio choices (2:1, 2.72, 5.33) whereas the Doubler is limited (2:1, 4:1). I have read that other brand boxes (NWF, etc), while fine products, work best with an external oil pump for sustained hwy driving - the Magnum does not need this.

 

[legopnuematic]

If I’m not mistaken, a SM465 internally is the same from a 10 to 60 series truck. So no strength advantage from getting one from a K30 vs a K10.

A K30 with auto hubs would have a synchro 205, which my understanding is that is not as desirable as a regular 205 due to lack of parts availability/support. A K30 with manual or full time hubs would have a regular 205.

 

[bucket]

Long road trips in a square with no OD (hopefully has AC and cruise with the 8.1 swap) feeding a 8.1?
How about option 12? Find a nice used GMT400/800 3/4T 4x4 burb. Slap a lift and some big tires on it and let er rip.

I don't have a calculator here in front of me, but 37's with 3.73's and no overdrive is probably very comparable to stock tires, 3.73's and an overdrive trans.

 

[bucket]

If I’m not mistaken, a SM465 internally is the same from a 10 to 60 series truck. So no strength advantage from getting one from a K30 vs a K10.

A K30 with auto hubs would have a synchro 205, which my understanding is that is not as desirable as a regular 205 due to lack of parts availability/support. A K30 with manual or full time hubs would have a regular 205.

I believe the medium duty trucks got a larger input shaft, but besides that, the same.

 

[Grit dog]

I don't have a calculator here in front of me, but 37's with 3.73's and no overdrive is probably very comparable to stock tires, 3.73's and an overdrive trans.

I’d say you’re probably right. And as an added bonus it would certainly achieve the goal of being character building.

 

[Zelph]

traveling with children. I would save the 2k and use it as needed after you complete the 8.1 swap. Spend that money on making it reliable. Breaking down with kids in tow is not fun.

 

[Hunter79764]

I don't have a calculator here in front of me, but 37's with 3.73's and no overdrive is probably very comparable to stock tires, 3.73's and an overdrive trans.

That was my thinking, 37's makes for the equivalent of ~.85 OD ratio vs stock, and 1st/low gear becomes a little more than useless. Still no highway cruiser, for sure, but not as crazy at it seems if I put the two together, pretty much a 4 speed with OD.

Just my .02 on a few things....

#2 Manual Swap - I wouldn't stress about getting one from a K30. These combos are basically the same for 10/20/30 series trucks with the exception of yokes. The vast majority will be 10 spline and you'll need to check the trans tailshaft for spline wear but these are cheaper than the later 32 spline units which bring more money. '85+ combos use the short foot, round pattern adapter and are typically a good bit more expensive than the older 10 spline units. 10 spline units can be converted to 32 spline for probably less than $500 if you just want the bigger spline count.

#4 Suspension Lift/Upgrade - be careful what you ask for with 52's, that can be a deep rabbit hole of long travel driveshafts, steering mods, etc. I have 2" lift 52's on my Blazer (dedicated wheeler) and it rides like a boat, lots of body roll and rocking front to back. It's not unstreetable by any means but I don't think I'd travel in it. A quality off the shelf kit can be made to flex a little more than average and ride well.

Doubler: I have one (ORD) and I've very happy with it, it's very beefy so I have zero concerns about breakage. That said, if I were to buy something today I'd probably get a Magnum instead. Underdrive boxes like the Magnum have greater versatility because of more ratio choices (2:1, 2.72, 5.33) whereas the Doubler is limited (2:1, 4:1). I have read that other brand boxes (NWF, etc), while fine products, work best with an external oil pump for sustained hwy driving - the Magnum does not need this.

All 3 points understood and appreciated. The K30 comment is mainly to make sure I get the NP205, I'm generally a fan of getting as many pieces together as possible since the nickel and dime stuff seems to kill projects more than the major parts. And I hear that the 10 spline are weaker etc, yet there is a fair shortage of people who actually break the 10 spline (although there may be something to a theory that the coupler gets dirty, wears out larger, and begins to slip at some point). I believe ~85 and up got the hydraulic clutch, which I THINK would be an easier retrofit in my 87 suburban, but I'm not sure. And I'm not sure if the hydraulic is really an upgrade vs mechanical linkage? I'm open to input if/when I get there.

I have had those concerns with the B52 swap, so I'm glad to hear feedback from someone who has experience. I take your comment as a vote towards lift springs based on intended use?

And you aren't the first to say that about a magnum box vs doubler. Maybe the reality is that I need to find a used doubled setup and run it pretty well as-is, or save my pennies and get a magnum box and maybe see if I can gear the axles to take advantage of it? i.e. a 496 with 500 ft lbs just off idle, a 5.33 transfer ratio, 6.55 1st gear, and 35-37's keeps an insane crawl ratio even with 3.08's, which would get my highway RPM way down. I don't know that my odds of finding a Dana 60 and/or 14 BFF with 3.08's is very good, so I'd have to add the cost of regearing, but it's a thought, for sure.

 

[Hunter79764]

By the way, here is a calculator that really helps with gear/transmission/tire decisions. A guy on another forum posted it, and I absolutely love it.

Gearing Analyzer with Shift Tracer

Enter gear ratios, tire and diff ratio to analyze RPM vs velocity at shift points with tracer

www.blocklayer.com

The mother site also has a ton of other calculators than can be useful.

Blocklayer.com - Calculator App Directory

Calculator Apps for Home Improvement Remodeling Construction - App Directory

www.blocklayer.com

 

[nvrenuf]

Yeah, '85+ are all hydraulic and the bodies are dimpled where the clutch master cylinder mounts and on the trans hump where the shifter hole is. I retro fitted a 4spd in my 91 Blazer and it was super easy.

The hydraulic pedals are nice and operate smoothly but I can't say they behave very differently from the mechanical pedals in my old K10. There is certainly a difference in pedal feel but the operation is no different (assuming the body mounts are good so there is not different movement of body vs frame).

If I was building a street truck to do light wheeling or overlanding I'd use an off the shelf lift kit with good shocks (ie; not Rough Country). You can move the front spring, rear upper hangers to achieve a better shackle angle giving improved ride and a little more flex.

As a set, the highest matching ratio for a D60 / 14 bolt combo is 3.73.

 

[SquareRoot]

Well, whatever you decide when (if) it ever gets finished it will cost 3x the budget, take 3x longer than expected, still get 10 mpg, still be hot, rough and noisy and the best engine oil will still be 10W40. But hey, that's how you build character

 

[bucket]

That was my thinking, 37's makes for the equivalent of ~.85 OD ratio vs stock, and 1st/low gear becomes a little more than useless. Still no highway cruiser, for sure, but not as crazy at it seems if I put the two together, pretty much a 4 speed with OD.



All 3 points understood and appreciated. The K30 comment is mainly to make sure I get the NP205, I'm generally a fan of getting as many pieces together as possible since the nickel and dime stuff seems to kill projects more than the major parts. And I hear that the 10 spline are weaker etc, yet there is a fair shortage of people who actually break the 10 spline (although there may be something to a theory that the coupler gets dirty, wears out larger, and begins to slip at some point). I believe ~85 and up got the hydraulic clutch, which I THINK would be an easier retrofit in my 87 suburban, but I'm not sure. And I'm not sure if the hydraulic is really an upgrade vs mechanical linkage? I'm open to input if/when I get there.

I have had those concerns with the B52 swap, so I'm glad to hear feedback from someone who has experience. I take your comment as a vote towards lift springs based on intended use?

And you aren't the first to say that about a magnum box vs doubler. Maybe the reality is that I need to find a used doubled setup and run it pretty well as-is, or save my pennies and get a magnum box and maybe see if I can gear the axles to take advantage of it? i.e. a 496 with 500 ft lbs just off idle, a 5.33 transfer ratio, 6.55 1st gear, and 35-37's keeps an insane crawl ratio even with 3.08's, which would get my highway RPM way down. I don't know that my odds of finding a Dana 60 and/or 14 BFF with 3.08's is very good, so I'd have to add the cost of regearing, but it's a thought, for sure.

You and I have a lot of the same goals. Really, most of the goals are the same. Except I want more power available, so there will be an overdrive unit in front of the SM465 and 4:56 gears in the axles, and tires in the 35"/36" range.