I am going to be swapping out a turbo 350 trans and a np 203 t-case(already converted to a part time) to a 700r trans and a np 205 t-case. I have been studying this for about a year now and think it is about time to try this task. I just got my crate engine in and running and want to do the swap before I put 3.73 gears in my pumpkins, so I can get back to some sort of gas mileage if there is such a thing in these old iron horses.I have read and ask all sorts of questions about this,everything from the TVI cable, to drive shaft mods,to converter lock ups,and everything you can think of. I have got all of my parts from The local bone yards and have about two of everything that I think I might need.My question is has anybody out there preformed this and is there anything that I need to pay close attention to or is this just one of those GO and figure it out things. I have never done a drive train swap like this before. Thanks D
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TRANS/T-CASE SWAP 77 4x4
- Thread starter D HELMS
- Start date
" b.i.t.s.a. "
I've been doing just what you're contemplating since the 1960's and if you have the patience and correct mindset , it's not only fun and rewarding but *very* educational .
Just jump on in and take your time , expect to get stuck occasionally , no worries just SAVE EVERYTHING until it's done and on the road for a month or three before tossing out even those nasty rusty & bent bits .
Double check all fasteners as it's easy to skip one and forget to go back and final tighten it after all else is lined up .
WORK SAFELY !! no bricks , cinder blocks tree stumps nor working on dirt or asphalt .
I've been doing just what you're contemplating since the 1960's and if you have the patience and correct mindset , it's not only fun and rewarding but *very* educational .
Just jump on in and take your time , expect to get stuck occasionally , no worries just SAVE EVERYTHING until it's done and on the road for a month or three before tossing out even those nasty rusty & bent bits .
Double check all fasteners as it's easy to skip one and forget to go back and final tighten it after all else is lined up .
WORK SAFELY !! no bricks , cinder blocks tree stumps nor working on dirt or asphalt .
GonicGM
Member
Most TH700R4 were ECM controlled, but not all. Diesel was not and 82-84 C/K20/K2500 with C6P HD chassis and gas engine did not. To find one of these 82-84 trucks with all the wiring would lend itself to your application. These trucks used a brake switch to disengage lockup, a 4wd relay to disengage in 4wd. Lastly, they use a vacuum switch to engage/disengage based on engine load.
GonicGM
Member
There was never a TH700R4 factory coupled to a NP205. Both the TH350 and TH700R4 have 27 spline tailshafts. One issue you are likely to encounter is a TH700R4 tailshaft short enough to properly engage the OEM TH350 NP205adapter and coupler. I believe advance adapters makes a proper tailhaft or coupler.