Mike you said a ¾ ton right, are you talking about a front hub or rear??
I have seen the fronts packed with chassis grease and this will turn to liquid and run back into the inside of the drum when it gets hot. The back could be the seal or gasket leaking allowing hypoid grease into the drum. And you seem to stress “pads”, is this not a stock brake system on your truck, it should have “shoes”.
Denny G
