I can't say if other Oaklands leak that much. On mine I need to dump the sump oil after every couple of hundred miles or so. Easy to do just open 4 petcocks on the pan and it drops the oil down to the correct level. that prevents a lot of the dripping. When I forget though, and the oil level gets too high, then it drips out the rear main quite a bit. The old transmissions are also tough to seal as they mainly used felt seals. There's always some dripping from them. However I've driven my Oakland now since 1988 and I've never felt the oil dripping to be an issue.
Ken