My boss found it. It is an American Standard Re-Nu trim only used on the B-349 valve. You can see its number 49 model 31223.02 and the grey shading looks like it is only offered on that valve model. Anyway, in case anyone else ever dives down the rabbit hole, I wanted to share the conclusion. Customer will need to find an aftermarket trim. I really appreciate your help @Sylvan. Thank you!!