Cool truck. Those aluminum bodies last forever.
It looks to me like the seal is not leaking. It looks like it is leaking between the yoke & the shaft. You might try taking the
pinion nut & washer off, clean it with some brake clean & put some RTV sealer under the washer & tighten the nut down real tight. There is no crush sleeve in that rear end.
If you do have to remove the flange there is a gasket behind it. They are never reusable. If you can't find one a thick bead of RTV will work.
George
Last edited by Wrenchbender Ret.; 08/01/2023 4:18 PM.