Dan the Gear Man® Tech Note 1:
Starting in the 1970's, Dana-Spicer switched from light gauge steel covers with embossed mating flanges to heavy gauge covers with flat mating flanges. Gaskets were used to seal the early covers, but the late covers used RTV sealant instead of gaskets. Due to the Design of the older covers, you MUST use a cut gasket for a leak proof seal between the cover and diff housing. With the late, flat flange covers, you can use either RTV or a cut gasket or even a combination of gasket and a thin film of RTV sealant. The advantage of RTV, is that properly installed on clean dry surfaces and using a grade of RTV that is resistant to gear lubricants (see S82194 RTV), it will not leak. The disadvantage is the covers sealed with RTV are hard to remove at the next service interval and once removed, the RTV residue stuck to the mating flanges must be laboriously cleaned off both surfaces. Many people now use a cut gasket with a thin bead of RTV on each side which simplifies removal and cleaning but still provides a leak-proof seal.
Dan the Gear Man® Tech Note 2:
QU42028 Dana 44 Reusable Gasket is manufactured by Dana-Spicer. These excellent gaskets feature a woven steel core, non-asbestos facing, and are coated with Teflon® so the gasket does not stick to your axle housing or cover. Do NOT use RTV sealant with reusable gaskets!
Dan the Gear Man Tech® Note 3:
Matching Parts for QU40214, QU42028 Dana 44 Diff Cover Gaskets:
Bare Front Axle Housing 73-75 F-250 Dana 44 Closed Knuckle 3300 pound Front Axle
S82194 RTV Sealant (Not for use with QU42028 Reusable Gaskets)