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Turbo 400 into 1980 Trans Am?

04/29/2019 10:15
Can I put a Turbo 400 into a 1980 Trans Am by using the '70- '74 T-400 cross member? Will it bolt up the same? I read that the sub-frame might be wider due to the catalytic converter. There is a 1978 Pontiac 400 engine in it with a T-350 that needs replacing and the T-400 would be my choice for an upgrade.
04/30/2019 09:51
It's been close to 20 years since I replaced a th350 with a th400 in my 78 TA. I can't recall the crossmember being any problem....
05/06/2019 14:41
Ashley did you use a '70-'74 stock cross member? If so I would imagine you just had to drill new holes and slide it back?
05/07/2019 10:35
I *think* I simply reused my 78 crossmember.
05/24/2019 11:06
I found this on www.crossmembers.com. Distance between frame holes is 30 1/2 inches on 70-74 and 31 3/4 inches on 75-81. One possibility it to cut the TH350 mounting tab off the front side of an existing 75-81 crossmember and welding on a TH400 style tab to the back side.
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