The US EPC says that the same axle part number 126 350 65 10 (same left and right) that applies to the 560SEC applies to all 86-up US-spec W126 V8 models (coupe and sedan). The caveat is the US EPC only lets me check cars with the 420 and 560 V8s. If 500s were available in Australia beyond 86, they might have a different part number. I doubt it if the 420 and 560 use the same axle. 6 cyl gas and Diesel W126 models show a different axle part number.

Sixto
95 S420
87 300SDL