Its a moen. The stems are held in by a plastic ring......(moen junk) they make a tool that inserts and you unscrew it. You can make a wrench for it also with some coppa pipe. Call Moen and they will have everything you need,including the handle rebuild kit and the wrench to install the new stems they will send you. I'm sure they will send you a spout also.
Thats a Monticello. Two handle tub and shower valve. polished brass and chrome.