you can do it and use only 4 of the bolts but they are not the same and you will not have much for strength doing it that way.
as long as it is a chevy bolt pattern th400
No.
Any automatic trans from Buick, Oldsmobile, Pontiac or Cadillac will bolt right up. A Chevy transmission will NOT bolt up without and adapter. If you change from a TH350 to a TH400 you will have to change your drive shaft yoke and the cross member. Unless you just have one lying around, or find and extremely good deal on one, there is just about no reason to put a TH400 behind a 301.
same bolt pattern if the 4l60e was behind a v8 or 4.3and the th400 was from a chevy and not a (bpo or caddy )
Sure, preferably a short tail TH 400 with the Chevy/Buick bolt pattern.
only a Buick, olds or Pontiac engine will bolt to a Pontiac tranny as Chevy blocks have a different bolt pattern.
Yes, it will.
No. The Pontiac headers will not bolt up to the Chevy small block.
No...it will have the bolt pattern of the Pontiac, Cadillac, Olds and Buick. Chevy has a different bolt pattern. There are some transmissions that do have the dual bolt pattern, but I don't think the TH 400 was one of them.
NO. It will not bolt up.
five
Some Pontiacs came from the factory with Chevy engines. If this is the case on your 79 firebird, then the transmission will bolt up to a 350 Chevy. If the car came with a Pontiac engine, then the bolt pattern is different and would not bolt up.