We just put in Delta temperature-controlled handles with Moen shower heads, works great. Delta has a lot of options with newer temperature control technology. Are you down to the sheetrock there? You might be able to replace more of that valve and get a better working system if you can replace things further back into the wall.

Thanks for the prompt reply. No, that's the shower wall (not sheetrock). I would like to not replace the valve itself. I can turn it with pliers and it works fine. I am just unsure which trim will fit/work with old valve.

Look like a Moentrol, but it's hard to tell without dimensions.