Just in case anyone is hunting for an original FEL-PRO 2 piece rubber (neoprene, whatever - lol) seal, I found this older
1928-80 FEL-PRO Parts Catalog on the interweb. It lists the FEL-PRO # "BS 13363" as their back then part number for the seal for both the 235 (1955-63 - their designation) and 261 applications from 1954-62. Oddly their catalog lumped Chevrolet and GMC trucks together under the "GMC Truck" category.
The link is a great potential source for identifying old FEL-PRO part numbers if you're hunting some no longer offered products.
Best of luck Craig in tracking your seal down.
