I Need Price Pfister OLD Flowmaster flowmatic parts

My old Flowmaster recently broke and I found a replacement mixer valve and handle, but I need a replacement trim plate to go behind the handle so water doesn't get inside the wall. I cannot find the part here in San Diego, I am told that Price is not making it anymore. Anyone know where I could get one or one that would work?

I believe you are talking about the "FlowMatic" ( cartridge held in place by 5 small screws). It is very old, and I have not recently seen any available parts, except the cartridge and the handle. You could try a big plumbing supplier, or you could go to Home Depot, and ask someone to break out the Danco catalog. Yes, they have a complete Danco catalog, and can order anything found in there. But finding an apron guy who knows where the catalog is....that could be a problem. Also try a goodle for Flowmatic.