I have a 69 X11 car with an 11A build date, and was wondering what the correct radio would have been. Also does it make a difference in the radio if the car has A/C?

What radio or if it came with one depended on what the customer wanted. You either ordered the radio or you got a radio delete plate. So putting in an Am or AM/FM would not matter, unless you had the bill of sale, and thats where it would be identified.

No difference as far as I know. My AM fits right nicely and i have factory A/C

a/c didnt affect the radio. It was either AM or AM/FM flip face or it also had options for mulitplex 8 track system too that connected to the radio as well.