I have an 85 rx7 gsl with a 12a engine in it.
my 5 speed transmission rattles and growls in gears 1,2,3 and 5.
Looking for repair advice or even a used transmission.

 

Sounds like you have an input shaft bearing going out. It does not make any noise in 4th because in that gear power transfer goes straight thru the mainshaft instead of being bypassed down to the countershaft for gear reduction or overdrive. Loss of lateral load on that bearing and noise goes away. It is a very common problem on all of the first gen 7's and even on 2nd gen but not as bad. Check into overhaul options as it is a very easy one to fix and a used one will probably have some problems as well as they are all now at least 11 years old and most driven pretty hard.