Marty, I only remember the GG-1s... This was for a customer that the 5V failed. The cab is pretty short so I think there might be an issue with the PS-32 fitting, even on the diesel bracket. Unless you go with a smaller or flat speaker. Here is the final with a PS-2 3V upside down. That fit nicely, but you can see the top of board is at the fly wheel height. and just enough room left for the truck harness to swivel, with the 12 pin just above the speaker edge.
This was the FF-2. Looks like MTH only made 2 variations of this. Like a Y1 but with passenger effect.
It was neat with PSA "arriving in Philly, Villanova, off to Paoli". Brings back memories. G