th350 to 2wd th400 swap NEED HELP

[Iceman21]

Hey guys i have a blown th350 sitting in my blazer right now. I have a np203 a np205 and i also have a np208

I have a spare th350 with a spare np203 bolted to it.

My question is... Should i just put in my spare th350/np203 combo or what would i have to do to run the th400/np205 or even the np208..

I know its possible to use the 2wd case but what all do i need and what am i look in at price wise guys? Thanks!

 

[kennyw]

You would be better off throwing a rebuild kit in a th350 than converting the th400 to 4x4. The th350 is about the same effort to rebuild as rebuilding a dozen sets of drum brakes.

 

[diesel4me]

You'd need the 32 spline input on the transfer cases to run a TH400....they can be swapped in place of the 27 spline TH350 style ones...if your TH400 is a 2wd short tail version,I have read "some" NP208's with the correct adapter will bolt up to one..

I have a 2wd cased TH400 in my 82 K20,but I dont know if it used the original output shaft it had from its original application ,or if someone swapped a 4x4 version into it.(was in the truck when I bought it)..it has a 6 bolt diesel torque converter thats "correct" for the 6.2 in it,and it shifts like someone swapped the diesel govenor in it too most likely..it has no provision for the two strut rods that bolt to the bellhousing dust cover,(has a tin cover,not the cast one)-but it hasnt seemed to bother it,and I've plowed with it for 10+ years ..

That said,leaving it a TH350 is easier,to make the TH400 work you'd need the right adapter for the
t-case and move the crossmenber,and also probably have to make the driveshafts fit ,they are not likely to be the right length and the yokes on a TH400 use larger u-joints with inside clips...unless you had the whole TH400 setup from another truck I'd just stay with the TH350...

 

[Iceman21]

If it helps with anyone here i removed the cone on the end and the shaft sticks out from the case about 4" wont that accept pre '84 NP205 TCASES? my case is from a 77 with the th350 adaptor ( and 27 to 32 spline coupler )but i should be able to put a different adaptive or hell just bolt it strait to the case? Not sure on that.. I plan on putting 38's and a 383 so i would prefer the th400 over the th350.. But since i DO have 2 th350 maybe i should just use them.. But if anyone can tell me i can use the Th400 without diggin through and changing the tail shaft.. If Thats possible..