A wonderful product called "the right stuff", ends all your leaky cover woes. grin

As for the actual needs, if the carrier assembly (houses the differential and bearings) is all part of the front cover, the pinion bolts onto it anyway, so the carrier to axle thickness is not an issue. Now gaskets/shims where the pinion attaches, thats another issue all together. All depends on your setup really.

1956 GMC 370 dump " 'Tater "
1970 VW Volksrod "the Black Bomber"
2007 Chevy Avalanche
2020 Jeep Cherokee Trailhawk,
2005 Harley Davidson FLHTCUI

I dig all cars, old and new, whether they were hammered out of American iron, German steel, or Japanese tin cans. Being unable to appreciate them all is missing out on a world of great things.
But thats just MY opinion! :P