how was the original radio set up in blazer?

[cstanley]

i'm trying to do some investigation here. i worked the new blazer over the weekend. i pulled the am/fm radio to try to get it working. it looks like the original for '72, but it had " '76 chevy van" marked on top. i knew it wasn't original, b/c the SPID listed an AM as original. anyway, no big deal to me, as it looks like the same radio that would be '72 correct.

traced wire, replaced fuses, and viola! AM sparked to life. i can't get fm to work, though. on to my questions...

there is a factory speaker (works) just above the radio, but there isn't any punched openings in the top of the dash...just smooth.

were blazer speakers originally mounted elsewhere? why do they have this different dash? moisture protection? i thought i had seen a speaker on a blazer mounted below the dash once. is that correct?

even though there aren't any openings for the sound to come through, it still sounds plenty good, just reverbing through the metal dash top.

anyone know? sorry, no pics. i'm at work.