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77gmcjoe · 03-10-2005, 07:52 PM

I've just put a 400/205 into my truck, so maybe I can help.
I had a 400/203 combo I was going to use, but ended up finding a rebuilt 205. After finding a 400/205 adapter (got lucky there), I discovered the tailshaft of the tranny I had wasn't long enough to mate with the 205 tcase. The adapter between my 400/203 was about an inch thick, where the 400/205 adapter was about 6 inches thick. BTW, the tailshaft of a correct 400TH goes directly into the 205 tcase, no coupler needed. You do have to have a 205 that has the correct input, there were several different styles. Again, luckily, I was able to get the correct 400TH with the longer tailshaft to mate with the 205. You'll need a 205 shifter as well, it's totally different than the 203 version.
I know you said you weren't worried about driveshafts yet, but I'll tell you that mine are being modified right now (rear lengthened, front shortened). Can't wait to get them back so I can finally test drive it!

All in all, it was quite a PITA, but I'm hoping in the end it will be worth it.

Joe

03-10-2005, 07:52 PM	#2
77gmcjoe What do we get for $10? Join Date: Oct 2004 Location: Beardstown, Illinois Posts: 340	I've just put a 400/205 into my truck, so maybe I can help. I had a 400/203 combo I was going to use, but ended up finding a rebuilt 205. After finding a 400/205 adapter (got lucky there), I discovered the tailshaft of the tranny I had wasn't long enough to mate with the 205 tcase. The adapter between my 400/203 was about an inch thick, where the 400/205 adapter was about 6 inches thick. BTW, the tailshaft of a correct 400TH goes directly into the 205 tcase, no coupler needed. You do have to have a 205 that has the correct input, there were several different styles. Again, luckily, I was able to get the correct 400TH with the longer tailshaft to mate with the 205. You'll need a 205 shifter as well, it's totally different than the 203 version. I know you said you weren't worried about driveshafts yet, but I'll tell you that mine are being modified right now (rear lengthened, front shortened). Can't wait to get them back so I can finally test drive it! All in all, it was quite a PITA, but I'm hoping in the end it will be worth it. Joe __________________ 1977 GMC K25 400/400/205 1989 Chevy Suburban R1500 350/700R4 (work beater) 1994 Chevy K3500 dually 454/4L80 1996 Corvette LT4 350/ZF 6 speed 2000 Bonneville SSEI Supercharged 3.8 Liter V6 1966 Chevelle 2 door sedan (Needs major repair )