W124 differential swap and compatibility

[clarkn0va]

I have a 1985 300D (W124) imported from Europe. After an engine and transmission swap, I'm finding the gearing much too short and I'd like to swap out the factory differential for something with taller gearing. After some searching, it appears there is some variety of gearing that came with the various 124 models, and all are not necessarily interchangeable (ie, size differences).

I know that mine has a final drive ratio of 3.46:1 because it is etched on the differential housing where you would expect to find it. The cover shows a part number of R124 351 25 08, if that helps. Photos attached.

Goals:

1. ~30-50% taller gearing
2. Minimal modification to car. Ideally keep the same diff housing and just swap out gears. Failing that, a different unit that will bolt up to the same prop shaft and axles

Questions:

1. How do I verify compatibility of a potential target diff with my existing car?
2. Is there a master list somewhere that shows my options?