Hey guys,
I am doing a 2wd to 4wd swap on an 89 Chevy 3/4 ton. The truck currently has the stock 350/TH400 combo. To do the swap I was going to buy a TH400/NP203 combo that a friend has. But, in the meantime another friend has told me he has a brand new dual stick 205 case that he bought for another project that has the adapter on it to bolt to a TH400. So, I will have a 2wd Th400 and a TH400 with a 203 case. Which trans will be my best bet to swap, what will I need, and where can I get it?
Thanks in advance guys!

I would buy both the TH400/203, and the twin-sticked 205, then get a doubler adapter and wheel the hell out of whatever. :D Collect cans if you have to. ;)

I concur. the doubler would be nice, sounds like you have the room for the extra length.


If you have to pick one or the other(you don't want or can't afford a doubler) then it's a no brainer to go with the twin-sticked NP205. It's stronger, and selectable, unlike the full-time 4wd 203.

That is a very good point that I never thought of. I've looked into the conversions and they are expensive. My buddy only wants 300 bucks for that new 205, so I guess i'm getting a pretty good deal there....

It's an alright deal. The twinstick mod is free. :D That adapter is pricey though... You did ok.

I'd also go with the 205. Sounds like your driveshaft lengths aren't an issues since you'll be fabricating from scratch anyway with the conversion. The only stickler I see is that you will have to

a: -cut the output shaft on the 2wd th400 to length to fit either transfer case, or

b: -if you can't cut the shaft to make it work, you'll have to tear down the tranny to install the correct length output shaft. There's a lot of info here on this swap. Keep diggin'....

We've got our 203 205 kits up for $599 right now, pretty much as cheap as your're ever going to see them. Here is the vendor ad: http://www.pirate4x4.com/forum/showthread.php?t=734754