I have a hous built in the late '20s with separate, back-to-back shower and tub enclosures that share a common water supply. We recently began a bathroom remodel and wish to switch the faucets from the old-style washer to a ceramic or cartridge valve. It was simple enough to replace the shower faucet with a newer setup, but the tub is trickier. The water supply for the tub is shared with the shower and actually passes through the casting for the tub valves and spout on the way to the shower. Apparently, these "pass-through" casting are not available anymore - or if they are, I have not been able to locate a supplier. Any suggestions on a viable replacement would appreciated.