The overdrive transmission I plan on using is a 4 speed and it was available in GM vans and pickup trucks from 1982 and up, and the shifter is on the floor not colume, it comes up next to the doghouse in a van like mine.

I still don't know about the crossmember,? by the last few posts I would think that the transmission will fit in place of the 350 turbo.

As for putting in a automatic overdrive 200R4 or 700R4 I don't like that idea, they have a poor track record.
I would rather go stick, lots of folks on this site are going backwards when it comes to there vehicles these days thats what this site is all about.