I have 3 coils all from different cars...what does it mean when on the side of the coil is stamped "3A" from an 86 ea82 carb/ "5A" from an 86 turbo/ "8A" from an 85 mpfi/NA

The only differenece is the blue topped subaru coils are made to run WITHOUT the like ballast resistor that wires into the positive on the coil

 

A coil is a coil. Almost any coil will work, it will just be higher/lower voltage then a stock subaru one. All the accel coil is that everyone uses is a coil for a standard V8 Chevy 350. puts out 45,000 volts instead of 36,000 like the stock subaru

 

The roomates 85 Brat is running off a coil from a 88 SPFI wagon so any of them will work