How many using an A500 overdrive ?

Just to add to this. The slant six never had a electrically controlled lockup (except maybe in a truck). That trans did not come out untill after the slant six was discontinued in cars (the electrical trans was not before 1988). I have a electrically controlled lock up V-8 904 trans, and a couple of slant six lockup transmissions. At some future date I am going to see if I can put all the V-8 guts (mechanical parts can swap, I don't know about the electrical parts) in the slant six case.
The oldest vehicle I've ever had with the electric control lockup was my 88 D100. 1st year of the TBI on a 318. The switch for the lockup looked suspiciously like a temp sending unit in an older /6 or 318