Hi,
For some trouble shooting I pulled a 951 ECU from a wreck to put in my 92 240 with the LH 2.4 injection (no cold start injector) and the 561 ECU. Car runs fine with the 951 but it did not solve my problem. What is the most current of these two units and which would be the best to keep in the car. I will sell the other.

thanks

The 951 is better (long term reliability) and more easily sold. Better to keep and better to sell, so there you go. This preference is base on my experience with large numbers (n ~ 100) of these ECUs from recycled cars. Very rare to see a bad 951 but occasional bad 561 white label ECUs I have seen. Pink label 561s I won't even touch.

If your 561 has a white label, then either is OK for your car. The 951 just has a few less parts on it (the CS injector parts).

I believe your 92 would have been built with a white label 561. Don't know which of the two is worth more on the used market. AFAIK both have the same application.
--
Art Benstein near Baltimore

Drive-In banks were established so most of the cars today could see their real owners. (E. Joseph Cossman)