There are three different variants to look out for

1) With out ABS
2) With ABS
3) With ASR and ABS

Then you need to get the final drive ratio the same as what you have now to make your speedo (at least) work correctly. The final drive ratio is stamped on the casing near to the rear cover.

Rebuilding a differential is possible but if the parts are really worn then it is probably cheaper to buy a new one at however many thousands of euros / USD Mercedes wants for one.

Finding a non whining W201 / W124 differential is an art!

If you want a rebuild thread I can link.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!