More good info, thanks gsxr! I've located a local to me 1993 400SEL with the ASR 2.82 diff for $100 if I do pick up this W124No, for multiple reasons. Mostly the 1992 500SL does not have LH injection, it has CIS-E mechanical injection, and the computers are not interchangeable. A module from a 93-95 500SL/SL500 would physically plug into a 400E, but would have the wrong fuel curves, and would lack the signal to the 400E-only first gear cold upshift delay relay.
The 5.0L LH modules are interchangeable between chassis that originally came with a 5.0L engine, although there are minor differences in programming. The 4.2L W140 (400SE/S420) module would not work properly in a 400E due to the relay issue mentioned previously.
Bottom line... get the correct module. They aren't expensive.
From what I've read on this forum and others I need the LH module with one of these part numbers: 014 545 15 32 or 012 545 15 32 and the build date for the module should be pre 7/1992. Does that sound correct?
Would 17" AMG wheels fit on a 400E or bad idea? I saw a cheap set locally from a W210 E320. I'm getting a little ahead of myself here I know, but just trying to learn more about these cars.