Cartridge issue

[wlr21]

Im trying to change an old tub facet out and the cartridges don't match. I have access to the bottom, but i cant seem to find the answer online. i attached photos. Please help

 

[TomFOhio]

What brand of faucet is it. Sometimes you can take your stem to a supply house or a good hardware store
and hopefully they can match it up for you. Is the washer shot on the end of that stem. Maybe all you need
is a new washer and seat. Hardware stores have a good seat selection.