I think you will run into issues once you get into the 94 model years as there is a time when they transferred over to the 95 style ecus. Most (if not all) OBD 1 style ecus between 91-93 will work just fine. No need to match up years.
If you look on Nismotronic's website, it lists ALL the ecus which are compatible
I am currently using a 91 SE-R ecu in a 98................
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91-93 Nissan Sentra/SE-R/NX2000/Pulsar B13,N14,N15 SR20DE Manual
ECU Part Nos: 64Y00, 64Y01, 67Y00, 68C00, 1N960
91-93 Infiniti G20 P10 SR20DE Manual
ECU Part Nos: 62J00, 62J01, 77J00
91-93 Nissan 240sx S13 SR20DET Manual
ECU Part Nos: 50F00, 50F01, 50F05
91-94 Nissan 240sx S13 KA24DE Manual
ECU Part Nos: 53F00, 53F01
Nissan Pulsar RNN14 SR20DET
ECU Part Nos: 54C00, 54C60
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