I realize this is late, and your issue is with the diverter. I just replaced the shower hot and cold handle cartridges on my three handle system. It is very likely it is the same system for your coach.
Brand for mine was Phoenix, the hot cartridge was 27873, cold was 27874 and the seats were 44786 (1/2"-20 x 1-7/32") It looks like the have the parts on etrailer. Those numbers could be just the local stores SKU. Phoenix Stem & Bonnet Assembly 9-43-5-0 could be the same thing.
I forgot to take pictures of the new units but just have the old.