OLDS Olds 425 trans?

[fleming442]

If you're doing a full build, you can offset grind the crank to a Chevy rod journal, which opens up your rod choices as well as being 4.24 (455) stroke. That's what's in my 468.

 

[L92 OLDS]

Is there a drawback to a steel crank?

No drawbacks. It's a good thing. Most cranks are cast or nodular iron. Your 425 has one of the strongest OEM Oldsmobile cranks out there.

 

[olds307 and 403]

Nothing was done to the th350 it is a TCI Street rodder New in the box

That trans should hold up but you will need a bell housing adapter unless you got lucky and it is a dual pattern TH350 both mine are, they do exist. One is I'm pretty sure original to my 70 Cutlass and the other is a 1985 TH350C out of a Caprice, so they existed all the years of production. Take a pic of the flange.