Hi, wondering if I dug out the crud is there an oil seal that would just fit into the circumference without having to drill out the 3 rivets, .
I don't think so. The rivets are obtainable and getting it all apart will make it much easier to fit the seal. Order the seal and see how flexible (or not) it is before deciding.
I replaced it for a modern oil seal, found in the automotive shop. It was a pres fit , through the backside before the gearbox was on.
Had a strange hole in the back of the primary, which i blokked off.
Found a picture from 9 years ago. But isn't possible to upload, sorry
thanks.