Joined: Tue Oct 11 2005, 01:33AM
Location: Calgary, Alberta
Posts: 5893
I don't know of any Mopar type overdrive transmissions, but a number of owners use Gear Vendor overdrive units on their existing transmission. Worth a look.
Joined: Sat Aug 19 2006, 05:03PM
Location: Ontario, Canada
Posts: 2919
If you're talking big block, there are no easy/cheap answers. Gear Vendors on the back of your 727, as Bill said. Chrysler A518 with adapter plate or custom bellhousing. Last weekend I was talking to a guy who had a GM 700R4 adapted to mate behind his stroked 440.
You have to cut the existing bell housing off your R-4 trans. I imagine there will need to be modifications to the chassis.
There are several options for small block 4 speed overdrive but require a lot of modification to the body and chassis.
A member here did an excellent job. Used a modern drive train in an early 70's wagon. I believe it was his Grandfathers car. Did a wonderful build thread here somewhere. Maybe some one better than I at searching will chime in and give a link.