Need replacement tub drain stopper but not sure which type

[EdHitchens]

New home, and the tub is missing the drain stopper. There is a center bolt in the drain assembly, but I'm not sure which type of stopper would have originally fit this setup (twist and turn?). Or maybe it's broken and I need a fresh new kit? Does anyone know? Sorry for the dirty appearance. The drain is 1.5", and the top of the bolt extends to just below the top of the drain. Thanks.

 

[Tuttles Revenge]

That bolt should unscrew out of the cross. Then I think all of your modern stoppers are setup to fit that bolt pattern. Its either 1/4 or 5/16th.. I prefer a lift and turn style.