I cannot find anything addressing this question: I have an August 69 Muncie M20. It was originally installed in a Camaro. The side cover is a 3952648 used on 70 production. Where the solenoid would be located on the shift fork boss, this has that part in the casting, but it is not machined (drilled, tapped or milled).
My question: do late production 69 transmissions use this side cover or has it been replaced?