1960 390 Engine to 1958 Transmission

[druby]

Will the Cadillac 1960 390 engine match up with a 1958 Cadillac transmission for use ?

[Roger Zimmermann]

If you intend to use that transmission in a 1960 car, it's a no go: the 1960 transmission is narrower at the bottom; the floor is therefore shaped in a way an older transmission will not fit.
If the 1960 engine is going into a 1958 car, technically it should be possible.