I have a 1972 D200 with a 318 727 auto and a D60 with 4:10 gears. I would like to slide in an overdrive tranny in place of the 727. My issue is I know less than zero about Mopar trannies. Can someone enlighten my on what is out there and what would work with my application? Also, is there a good auto tranny out there by Mopar that is not electronic?