Rear Main Seal is made from a GraphTite rope material for the 1938-52 Buick 8 cylinder 60, 70, 80, 90 series. The RMS is not used from 1936-37 for the big series engines.
The long side seal is specifically for the large series engines.
Best set# 5143
Made in the USA!
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Buick 8 cylinder 60, 70, 80, 90 series Rear Main Seal, 1938-52, GraphTite