2WD trans conversion to 4WD trans
#2
A complete rebuild since the main shaft is too short in the 2wd. I found myself with the same issue when I converted to 4wd. I ended up just getting a 4wd tranny and I rebuilt that instead. Before I did that though I called around to many local driveline shops and all said the same thing, that I later found out when I tore both 2wd and 4wd 4L60E's down to the main shaft. The 4wd was indeed longer which makes sense considering it has to go through the 5 or 6 bolt adapter and mate up with the t-case.
#5
But chevytruck, to answer your question, you need to rip the tranny apart to the very last piece and then fully rebuild it to do the swap.
#6
If you have a manual tranny, it is doable. I swapped 2wd tranny for 4wd. The rest was mainly adding parts. i used manual shift t-case and only had to build one mount for front carrier due to broken mount. Wiring for front axle engage is just a toggle sqitch on dash.
#7
I did this for the TH350 swap in my K5.
It was only worth the effort because I was building to handle upwards of 450 RWTQ as well and would need the entire thing apart.
Also of note, some auto transmissions had stronger, ribbed cases for some 4WD models, but I only know of this with the TH350 and 700R4/4L60 transmissions and might not be the same for 99+ parts. I'm just throwing that out there, as you might just be better off with a 4WD case, if you can find a good one. If you need to rebuild anyway, find a cheap 2WD case and work from there.
It was only worth the effort because I was building to handle upwards of 450 RWTQ as well and would need the entire thing apart.
Also of note, some auto transmissions had stronger, ribbed cases for some 4WD models, but I only know of this with the TH350 and 700R4/4L60 transmissions and might not be the same for 99+ parts. I'm just throwing that out there, as you might just be better off with a 4WD case, if you can find a good one. If you need to rebuild anyway, find a cheap 2WD case and work from there.