BD - The original output shaft oil seal is listed in the 1957 Chevy Master Parts Book as GM# 8612229 with a 1-1/2" ID and a 2-3/8" OD (measured at the external section that presses into the tail shaft housing opening).

There are a few NOS seals offered on ebay, but a modern reproduction/replacement is offered as Filling Station # GR-573. The reproduction has a slightly larger outer flat face flange that serves as the seal into housing stop.

The 1957 Chevy Master parts book lists the same seal as fitting both the standard 3 speed (Parts Group 4.318) and OD 3 speed (Parts Group 4.460) output shafts under that part number.

I tried cross referencing your "5565J" number and didn't get any hits at all. Perhaps an old replacement stock manufacturer that is no longer in business???

~ Dan
1951 Chevy 3 window 3100
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