Can any one help me identify this stem...the shower body says" made in the USA".....and the shower stem has a number on it 584-c or it could be the other way around....It's 3 inches long and skinny.......this is a older model..... unit
Hard to tell from that pic. Thank you for taking the time to do that, and if you could either get a pic of the handles, or bite the bullet, turn off the main water and remove the stem, those pics would help a lot.
A lot of stems look alike - even the packing nut off the thing would help. But it looks like it could be a Briggs old style. Gerber has one similar to that, but it has a deep internal part that I don't think would fit your valve.
Well you have the wall open. You should just change the valve to a newer single handle pressure balanced anti scald valve. This would solve the head aches of hunting down an old stem. Let alone a stem that is hard to identify.
Good hardware stores and plumbing supply houses have books that you can use to try to match up your stem. Turn off the water and remove it and just bring it to one of those stores.
If you can't find the correct stem, you can repair/rebuild this one: Replace the bibb washer and seat, install new packing and packing nut.