Olds came with the 425 starting in 1965. The 64 was the last year for the 394 and the Slim-Jim hydramatic. Totally different animals, and totally different mount and frame system. In 64 Olds used a reverse triangle shaped pattern for the mounts, one up front, two straddling that useless transmission. The 3 speed Roto-hydramatic is a dog that I wouldn't wish on my worst enemy. 1965 was the year they modified their blocks to the BOP pattern and used the improved TH 400. I used to own a 64 Oldsmobile, traded it off to get my Wildcat.
Thanks Marc, wasn't quite sure which year the Olds 425 came out, '64 or '65? Sorry NHR, looks like you have some frame pad and motor mount fab work to do.
Olds "improved" the reliable (if inefficient) dual-range Hydramatic in '56. At that time they called it the Jetaway. As Marc says, it was a dog. You don't want one.
That's ok because the Olds 425 has the BOP bolt pattern so he can bolt the ST 400 to it that he already has. Or use the TH400 that came with it.
Sweet! The best of the best...Having 2 Switch Pitch TH 400s and having driven the non switch pitch variety, I much prefer the older ones. There's just that little bit extra. Now the problem you're going to have is in order for it to work right you're going to have to find what Olds did for switches and linkage. Or you can hook up a toggle switch and run it that way.
In '66 the Buick THM 400 was not interchangeable with Olds and Pontiac. That didn't happen until 1967.
