one of my winter projects is to get pinion seal on rear end fixed. tried last summer, pulled it apart replaced with identical seal from FLAPS, reused the felt seal as it seemed in good shape. took it for a ride and still had a leak when it got warm. questioning if it was the wrong seal all along? Title for truck says its a 1948 3100. But, serial #'s on engine and tranny both say 1952. 8 bolt rims all around. I can only assume someone took a 1948 body/title and put it on a 1952 3600 chassis. hoping someone can identify this rear end to confirm and then attempt to find correct seal. Raised numbers on differential carrier: 3682126 stamped letters on top of "pumpkin" are very hard to read but I believe 16716? One piece of info I dont have on hand is weight of gear oil I refilled with. Could simply switching to a heavier weight oil remedy this issue? It only leaks when hot leaving a rooter tail of oil spun up onto underside of bed and then a small puddle of garage floor.

1948 3100 according to title.
1952 3600 under the body.
216 ci 6volt