Swapping Drivetrain

[Leitschuh]

Hey guys, I just did an engine swap on my 1983 chevy K10 from the factory 165 hp 305 to a built 350 with 320 hp. I also went with a two in lift and 32in tires. Now that I'm as far as I am, I'm worried the 700r4 and 208 aluminum transfer case wont like the new upgrades. Im wanting to swap to the M20 manual transmission and 205 iron transfer case to back it up. Other than replacing the steering column (so there isn't a dead shifter) and adding the whole clutch assembly, will i need to swap driveshafts to fit? Also is there anything I'm missing in the swap that i need to do? Just looking for some recommendations and help from people who have done it or know all the specs better than I do. Thank yall.

 

[Nonstop]

While I can not speak for the 700r4, the 208 can be pretty stout. It came factory in 3/4 tons. Ford also used them in their 3/4 tons and, I believe, behind the 460. Might be much easier putting in an NP241 if you are concerned about strength. It should bolt in with minimal, if any, modification.

I am partial to a stick, but it will be quite a bit of work and time that could be spent breaking in that new engine!

 

[Leitschuh]

Thanks Nonstop, would a m20 work with the 208?

 

[1987 GMC Jimmy]

I’ll speak for the 700R4. The later ones are good and could handle that power with likely nothing more than a shift improvement kit. I’m talking 87/88-92. The improvements became noticeable every so many years. 82-83 are notoriously bad. 84-86 are okay (‘85 700R4 in my Caprice has 280K miles and no signs of slowing down; tranny has actually outlived the torque converter). You could yank yours and build it up with all the upgrades to avoid modifications or rebuild a late model core. If you’re dead set on a standard, have you considered something like an NV4500? Not trying to steer you away from the Muncie, but just a thought.

 

[RoryH19]

My k20 had a NP208 with a 4 speed (granny) standard trans.
No problem with the t-case. It had 33x 12.5 tires.
The 700r4 will be the weak link.

 

[shiftpro]

What really kills the 700 is low rpm torque, towing, pushing snow, or too high a gear ratio (bigger tires) so it's hunting back and forth into overdrive. Also the TV cable will eventually stretch and sometimes enough to not fully increase pressure on the clutches, slipping and nuclear heat buildup = dead 700.

 

[Leitschuh]

Thank you guys for the feed back, so if i decide to do away with the 83’ 700r4, but keep the transfer case, would everything still fit together like the driveshafts or would they be a different size? Also, what would be the best 4 speed to swap it with that would bolt to the 350 engine and 208 transfer case