Somewhere at the shop, but you don't need a part number. Call Total Seal, ask to speak to Kevin, you will need to provide him with your bore size, ring thickness ( measure top to bottom), radial depth (measure outside to inside) get a second ring gapless set, and ask them for file to fit set, this will require you to file for the ring gap, use the ring gap formula for bore size from their instruction sheet. I don't think they call it a part number anyway, since it for them is what they call a custom order, and they asign a job number to whoever orders them, they get kinda funny about people sharing job numbers, they do this to protect the orderer, but it's no real secret. basicly Total seal doesn't make rings, just modifies existing rings to be gapless, so when you place your order, it will go in line to get machined (well the gapless ring anyway) allow a couple of weeks to get a set. It's a good product, you'll like em, I sure do. Call me Chris, if you have any questions and I'll try to help you, if this didn't cover it already