i am thinking of swapping the auto in my 70 GTO with 455 HO to 4 speed. can anybody give details on what parts will be needed? Also, will a muncie 4 speed work OK with a 308 rear gear, and will the steering column for the auto be the same for 4 speed?

i am thinking of swapping the auto in my 70 GTO with 455 HO to 4 speed. can anybody give details on what parts will be needed? Also, will a muncie 4 speed work OK with a 308 rear gear, and will the steering column for the auto be the same for 4 speed?

Do a search. It's been covered numerous times. It's a pretty simple, straight forward swap if you have all the parts.
The steering column is the same. You will need the revers lockout linkage which isn't very easy to find.
As for the Muncie, it depends on which one you have. The wide ratio M-20 would be the one you wanted. I would avoid the close ratio M-21 and M-22 (Rockcrusher).