I purchased inner bearings BR5 and inner seal 19630
and outer bearing BR3 from Kragen online for $44 (both sides, all six boxes).
Picked up in store.

These are SKF numbers.

But the store application listed the WRONG OUTER bearing and I figured
out that BR3 by having them check other years around mine and matching
the one I removed (had it in hand) with the ones on their shelf for
other year Mercedes, including checking the bearings for the gasoline models with the same body. Like 380sel or 420sel or 280c, etc..

(can't remember if it was the W123 or W126 at the time, but
they both use the same bearings).

I can't say for sure the 84 uses same bearings as the 83 but the story of wrong size sounded familiar.

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80 300D 340K Owned 30 yrs
83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day
02 Z71 Suburban 117,000
15 Toyota Prius 2600 miles
00 Harley Sportster 24k
09 Yamaha R6
03 Ninja 250