Does anybody know if the bosch ECUs # 0 280 000 561 & 0 280 000 951 are interchangeable?

My '90 245 with LH2.4 quit running, no spark. Initially, ign & fuel ECUs showed no fault.
I used my daily driver '93 245 with LH3.1 to swap & verify all ign components (ECU, amp, coil) & wires, plugs, cap & rotor are new.

Later the fuel ECU indicated no speed sensor signal so I replaced eventhough original metered fine(175ohms & I didnt want to swap off of the running car to verify). I was also able to put the ECU unit into diagnostic function 3 to test the pulled injectors firing, cold start inj & idle motor. All were working fine eventhough Bentley says that function3 is for LH3.1 only. Im sure the '90 is LH2.4 as the air mass meter & throttle sw are different from the '93.

Now, the ECU will not display any diagnostic codes (or function 2 or 3) so I'm pretty sure that its faulted.

I read a british volvo post that mentioned that most ECU failures are in the hybrid circuit which is the circuit that converts external 12V signals to 5V signals which the ECU chips work on. They recommended using refurb ECUs with improved hybrid circuits as opposed to junkyard oem swaps. I priced the refurbs at $550 (ouch) so Im going the junkyard route.

Im hesistant to swap 951 ECU from the '93 just to see if the '90 will run as it may become damaged & Ill be walking.

There are some wiring differences between the systems but Ive seen other posts in this site that indicate that there were some 2.41 models with the 951 ECU.

Any comments?