It doesn't belong in there. It's probably some ones idea of a seal if they may have had excess oil on the clutch.
There is no front seal in those transmissions. They rely on an oil slinger which is part of the nut that retains
the front bearing. There is a close tolerance between the inside of the bearing retainer that the release bearing
slides on and the slinger. If both are damaged or excessively worn oil will move out instead of returning to the case.
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine