Resealing your Alpha One Generation II Upper Driveshaft Housing Assembly is very much like
rebuilding the unit as the shimming procedures should be followed as when rebuilding.
Some customers elect to simply replace the seals and orings without checking the shimming of the gears and bearings. This is possible but not recommended.
To reseal your upper... follow the instructions at Rebuild Your Alpha Gen II Upper Driveshaft Housing Assembly but adjust your procedure as so the shimming process (and tools) are not required.