what is this part?
 

its some electronic module

has FB67 67 790 labeled on it.

Huh, dunno. Where'd you find it?

it was in my big box of rx7 whatnot. Trying to figure out what it is. Maybe start making a small database of oddball crap identification.

I think it may be the amp or equalizer for the stereo.

I know I've seen them before just don't remember right now. Doesn't show as a good number now, which usually means it is no longer available from Mazda.
I'll let you know for sure when in get back in the shop to check old parts books and fiche.

looks like the temp censor for you airconditioning. but im not possitive. if it is that it would explain why you have it thrown in a junk box

on second thought it could be for the automatic seatbelts if you have them.

It's a control box for 88 alarm. Mounts RF kick panel. That's what the fiche and Mazda dealer price list says.