I have a 72 blazer with th350 and np205. My problem is the tranny is pushing fluid into the transfercase. I have changed the seals that are on the adapter in between them once and had a shop do it once but the problem is still there. Any help would be great.

I had a NP205 behind a 465 tranny that did the same exact thing you are saying yours is doing. The NP205 that came with the manual 465 transmissions use 10 spline collar and TH350s use a 27 spline collar that conects the the transmission to the t-case. Mine was leaking through the splines. I hade to replace the collar ( the manual 10 spline collars and transmission shafts are prone to wearing out ) and I put some silicone inside the collar to keep it from leaking again, new seals will not keep it from leaking past the splines.

doesn't it have an O ring in the spline shaft? if not look to see if there is a groove for one it might be missing.

Where can I find a parts break down of the th350 hooked up to a np205 so i can get the part number on the oring.

thanks for all your help

I have had 2 different adapters for my T-350/205 combo.

one adapter had a seal in the center of the adapter, and the other one didn't even have a machined seal surface. Both of them being stock adapters. Is you vent clogged to the trans pushing the fluid into the t-case?

No the vent is not clogged. I havent pulled the transfer case down yet to see about the oring.

I have the same problem. Dropping the 205 down and replacing those seals was a PITA...only to have it still leak just as bad:mad3: The th350 will leak about 3qts of fluid into the np205 if let to sit for about 2 weeks. It doesn't leak more then the 3qts but that is just enough for the torque converter to not fill and the truck not move. I am almost pissed enough to fork over the $$$ to toss in a sm465.:mad3: