My vehicle: 1985 300CD-T (Calif.).

Issue:
The two output seals that fit onto the sides of the differential don't seat entirely. Puzzling.

I've replaced the rear axles and differential seals on a 300CD before (but quite a few years ago now) and don't recall the output seals being so difficult to install and not seating entirely.

For each seal, about 1/3 of it sticks up (maybe two finger nail thicknesses) and doesn't seat perfectly flush like the other 2/3 of the seal.

Is this lack of complete seating likely a problem? Say, going to be the source of leaks?

The brand of the seal, incidentally is Corteco.

None of the McParts places seem to stock these seals (which strikes me as a bit unexpected), so next option would be replacements from the dealer.

Prior to installation, I applied 75W-90 oil onto the side of each seal as well as onto the differential surface where each seal would seat.

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I also just replaced the two drive line flex disks and intermediate bearing and carrier. I must say, the carrier, manufactured by Rein Automotive, was junk! Talk about not being anywhere near Mercedes-Benz quality! It seemed like the manufacturing had been pimped out to the super lowest bidder. Good heavens! It is as if the jigs for the parts are so old now that they are drifting out of specification...