Any 90-94 turbo DSM ECU will work. The car will run with anyone of them. However, the 91-94 have two pins swapped (six and fourteen). One is for the idle switch and the other is for the Air Flow Sensor filter reset. In any event, the car will still run with or without swapping the wires in your harness.

The only difference between the FWD and AWD ECUs is, I believe, two resistors. They affect fuel trim marginally and you will not notice the difference. Ideally, you should acquire either a 90 AWD ECU or an EPROM.

Here are the ECU codes:

Manual AWD
3/89-6/90 - MD145903
6/90-6/92 - MD166262
7/92-5/93 - MD193299
6/93-5/94 - MD304484

California Manual AWD
3/89-6/90 - MD145902
6/90-6/92 - MD166263
7/92-5/94 - MD193295

Automatic AWD
6/90-6/92 - MD165531
7/92-5/93 - MD193300
6/93-5/94 - MD304485

Californial Automatic AWD
6/90-6/92 - MD165532
7/92-5/94 - MD193296

Manual FWD
MD128625
6/90-6/92 - MD166260
7/92-5/93 - MD193297
6/93-5/94 - MD304482

California Manual FWD
MD128623
6/90-6/92 - MD166261
7/92-5/94 - MD193293

Automatic FWD
6/90-6/92 - MD165529
7/92-5/93 - MD193398
6/93-5/94 - MD304483
MD193298

California Automatic FWD
6/90-6/92 - MD165530
7/92-5/94 - MD193294