.
It has been a long time since I last changed oil seals, but I do remember that it was never a quick easy job. I personally would always "Test Fit" the seals on the axle before hammering them into the hub. You can't
feel that fit while holding a hundred pounds of drum and cramming it onto the spindle. Hand fitting them first helps eliminate a sloppy or loose fit. That saves time and effort.
Wonder if the axle spindle has some wear on it? If so, maybe the shop could install what is called a "Speedy Sleeve" onto the spindle. OR maybe they bought the seal that should have been used with a sleeve and they got the wrong part.
Looking at the Parts TM, M809 SERIES -----------
-- Stand By. Replacing Information in my post
Picture on Page 235, Item #25. It calls it the Seal, Plain, Encased. Part Number -------
I don't have a M813 to go look at, but at least now you have the pictures and part number. I believe it is a Dana axle. That and a nickle is about all I have to contribute to the problem.