Matt,
Can't answer for the light gasket issue (others will probably chime in).
Also can't help with the radio questions (sorry).
However, concerning the transmission ID, looking at the picture you attached, if you look above and left of the 3 threaded mounting studs on that side there appears to be a very dirty "data plate" riveted to the case of the transmission.
Some gentle cleaning of the plate area to remove the oil and grime should reveal the ID info your are trying to pin down.
Let us know what you find.
