The O.D. tranny will have a third lever towards the tail shaft for which the control cable connects..Plus the electric solenoid is evident..The saginaw four speed is from the same family alright..I found a Petersons transmission manual at a swap meet and inside is a lot of ratio information..The gear ratios between the three speed and four speed are pretty much the same..But you gain the third speed which a inline six could really use..I found (three) four speed saginaws at a local yard for five bucks each..The owner said GM couldn't built a tranny that was any good..FINE BY ME !!..Anyhow I put one in a 65 half ton with a stock 1974 250..It is a gas to drive...Pun ??..Price for an overdrive ???..Not sure..I think for $250.00 it should be in good shape..Or should I say it BETTER be in good shape..I would still be pulling the side cover to check it out....Al..
