1990 ECU's

i pulled a 4g63t from a 90 eclipse gsx yeasterday and im wondering since the engine is from a 90 does i need a 1990 Ecu whats the difference's between 90 and the rest of the 1g's

A 90 car will need a 90 ECU but a 91-94 car will need a 91-94 ecu. Engine year doesnt matter IIRC. There are two pins that are switched around from 90 to the other 1gs and you can ghetto mod it you harness, but I wouldnt recommend it. I would just sell the ECU and get a new one.