I need help locating and American Standard Shower Cartridge?

The website and customer service are useless for the manufacturer and I have not been able to find the part locally or online. It is a shower/tub cartridge for a single white porcelain handle manufactured between 1995 to 1998 fastened with 4 philips head screws. There are also 4 outlet holes, the cartridge is a gray plastic/ceramic with the word "down" signifying the direction to install it. No model # or serial # to be found.|||I ordered one from a plumbing supply company even though I am not a plumber. Take the cartridge in with you so they can identify it.