Well I just bought a 85 olds with a Oldsmobile 307. On the way home though I think I blew it up. Anyhow. I was wandering what's the bolt pattern for the transmission on the olds 307. It has a TH350 that would work nicely with my firebird.

 

I could be wrong, but I believe that will bolt right up.

 

The Olds 307 has the 6 bolt BOP bellhousing pattern, I believe, while the Chevy 305 uses the 5 bolt Chevy pattern.

 

An olds/buick tranny will not bolt up to a chev block. They are different. I had a turbo350 out of my old regal, with a 301 for sale, and some guy asked if it would fit his 305, and I told him no. He drove down, 3hr drive btw. When he showed up, I told him again it wouldn't fit - bought it anyway. Got a call the next day complaining that it wouldn't work with his 305 in his Monte Carlo.


From 442.com:

"GM uses two bellhouse patterns (on real cars, RWD, '64 or so to the end of the V-8, outside of the early hydramatics):

Chevy. Looks like a mansard [barn] roof. Pointy at the top.
Everyone else. Olds, Buick, Pontiac, Cadillac. Not pointy on top, kinda flat, with about 7" between the top 2 holes.

The dual bolt patterns showed up when GM started to consolidate it's transmission operations and use "Chevy built" transmissions in BOP applications and "Hydramatic Built" transmissions in Chevy applicationas."