My procedure is this:

totally clean both surfaces, remove residue with brake spray.

apply a single small bead 1/8" thick around the inner perimeter of the cover, and set in place on the diff. barely snug the bolts by hand and let the cover sit for 30 minutes, then tighten fully.

the loose bolts allow the sealant to partially cure, and then final tightness makes it secure.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!