tub faucet leak

Thanks to anyone for a guess. I am having so much trouble identify this old faucet type to get a replacement. Its currently leaking. If anyone is able to identify it and where I could find a replacement I would be extremely grateful. Or if anyone has ideas on how to get it to stop leaking.

The tub faucet in our second bathroom is leaking from the wall side whenever the shower diverter is pulled up. It only occurs in shower mode, not when the water is coming from the tub spout. From what I can see by looking under the tub/into the wall from the Jacuzzi access panels, it is NOT...