You know, one of the problems with getting older is being forgetful. I took the cover off where the leak was happening and it was immediately obvious that I had never changed the gasket. So I made a new gasket, used a little Permatex 2A and put it back on. Will let it set over night and then put gear fluid in tomorrow night. It will probably fix the problem. Harbor Freight has those hole punch sets and say what you will about HF, these punches are fine. Third time I've used them. The whole set was no more than $5 and they work great for cutting out gasket bolt holes.

1953 Chevy 3600 3/4-Ton