# on ECU for ka24e to ka24de swap?

[240sx4roadrace]

First off, I have tried researching this, and still need help. I am getting ready to do a SOHC to DOHC. I am getting all of the needed parts. I bought an ECU from a guy, on the top there is a big # 30. (To be clear, I am talking about the 1/2 inch number on the Nissan sticker on the big flat gold part of the ECU, (not a diagnosis code)). I was told it was for DOHC with 5spd. While at the wrecking yard getting instrument cluster, I was in a 91 with a 5spd, and I noticed the number on that box was different. It has a 26 on it, so I took it just in case since I knew exactly what it came out of. Is there anywhere that deciphers those numbers? Or does anyone out there have all those numbers in their head and could tell me which one is the right one, or will both work? Everything I have seen on the forums refers to the ECU by being from SOHC or DOHC and if it was auto or 5spd., no ref to # on box. Or does the number mean absolutely nothing unless you know the year and transmission anyway?

Thanks