94 Infiniti G20 ECU, automatic?

I have an Automatic 94 Infiniti G20 with a manufacture date of 1/93. It needs a new ECU, currently it's at the shop so I can't get the Manufacturer part number. I guess there are a few different models of the car and each is built with a different alternator, ECU, etc.is there a website where I can get the part number by entering in the information? Or does any, by chance, know the part number?