According to the Germanstar dot net parts search, your amp (MB part 005 545 0532) was used in all 124's through 1992 and all 560SL's). If you get an amp from something other than a 2.5 Turbo, you'll want to use the coding plug on the amp you currently have.

Whether a DIFFERENT amp would work in your vehicle, I doubt it but am not sure.

Happy hunting! I just got one on Ebay for $20 including shipping that works perfectly.

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14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife