Transmission Swap Question

[sonicbluezx3]

I currently have a 700R4 behind my 6.2 diesel. I have a 86 K10, and I'm not sure what my transfer case is nor what my gear ratios are.

First question is how do I figure those out? Not to sound like a newbie but I don't have a lot of experience with that sort of thing.

My main question... I want to get swap the auto over to manual. I know 700R4s aren't that great, and I've always preferred to drive a stick over an automatic. I've done a full restoration on my truck minus the engine and transmission. I found a SM465 with granny gear near me for $200, all I would need is clutch, flywheel and pressure plate. I'd imagine since my trans is good I could sell it and get my money back pretty much.

Is that a good idea? Or I've heard of an NV4500 or something.

 

[MrMarty51]

If the 465 has granny low, You`ll want the NV4500 as it has overdrive, just be sure that the trans You get is a good one, it costs a lot to OH them 4500s, as much as an automatic.
Overdrive is good for the diesels, I think.

 

[philjafo]

The 465 is a great transmission, I would suggest trying to get the transfer case with that transmission. It should have a np205 behind it, wher the 700r4 likely has an np208. Not only will the np205 match the strength of the sm465, it will also be easier to bolt up.

 

[marks86]

check your glovebox for the RPO code should tell you your gear ratio

 

[bucket]

There's a lot of 465/208 combos too, and they bolt right in place of a 700r4/208 combo using the same shafts even.

 

[kleedus]

first year for the 465/208 combo was 85 they made the tailshaft longer on the 465 so the overall length of tranny and t case is the same as a 700r4/208 combo

 

[HotRodPC]

Before we go jumping onto the NV4500 suggestion.... Sure that's a great idea, but very expensive. So, let's decided what the truck is going to be used for first and how often it's driven.

Don't forget you'll need to swap out your brake pedal for a set of clutch and brake pedals.

Also, be sure you're getting a SM465 that is a 4x4 SM465 and not a 2wd unit. There are also different output shafts for the 4x4 SM465's so be sure you're getting the right one. If you do, then bucket is right. You can do this swap without need to mod your driveshafts. $200 is a bit steep IMO anyway. I see SM465's in working condition for $100-$150 frequently. The last one I bought, came with the bell housing and clutch for $50 and it was a 4x4 SM465 out of an 87. I needed the bell housing so I kept that for my A833 4 speed overdrive trans, and sold the SM465 for $100. Nothing like getting a FREE Bell housing, a rare one at that, and making a $50 profit.

But to answer your question, yes it's a reasonable swap so long as you know you're losing OD. Usually the 6.2 1/2 ton trucks have pretty tall gears since the Diesels don't like high RPM's. If it does, you might want to keep those tall gears, prolly like 3.08's. If you need some low end grunt, you'll always have the granny 1st gear. And if you need the grunt while off roading, you always have 4 Low which in the NP208 is closer to a 3:1 unlike NP203 and NP205 closer to 2:1 in 4 Low. So you'll still have low gears to compensate for the tall axle ratios. If you're towing, hopefully the 6.2's torque can help compensate for the tall ratio too. I know they lack horsepower, but they are still pretty torquey motors.

 

[bucket]

first year for the 465/208 combo was 85 they made the tailshaft longer on the 465 so the overall length of tranny and t case is the same as a 700r4/208 combo

It was '81, since there were no 203's or 205's used in 1/2 and 3/4 tons after '80.

 

[HotRodPC]

It was '81, since there were no 203's or 205's used in 1/2 and 3/4 tons after '80.

You're both right to the best of my knowledge. I wasn't sure of what year it was done, but there is 2 different SM465 setups for NP208's. I think the spline output is even different along with the length, and 85 sounds about right. If it's 85 and up, it's a direct swap with a 700r4/NP208. Same driveshafts, same crossmember location and all.

Worthy info to check into and get correct and put in one of the Trans Stickies for Trans Conversions since we seem to deal with it alot. I wasn't that long ago, someone wanted to go from SM465 to Auto. I sure woulda like to have swapped some parts with them.