Quad X ring for Thermoquad primary well seal

My one and only Thermo-Quad rebuild went well and the truck ran great. Then a few months later those well seals failed and it ran like crap again. I don’t remember the kit brand, but it was supposed to be a good one. Kinda frustrating
I did these TQ for a living in the 1970s and never had any come backs !!! USA parts ????