In order to keep it, sounds like you would have to remove the plug, drill a larger hole, thread it, and then use a matching screw. If you know a mechanic, that person would probably have the tools to visit and do it. (this is the kind of task shown on "American Chopper", etc.)

Thanks! The problem leak is from the spout while the water is off, which we initially thought was valve-related, but doesn't seem to be now that the new valve is in and it hasn't stopped. It's a slow but steady drip. We do also have problems with a steady but small stream of water from the spout while the shower is running (and with a small stream of water from the shower while it's not supposed to be running) but those stop when the water is off, so I'm less concerned about them.

Manufacturers describe things differently at times, but look for a "4-port diverter valve". One port will be water in, the other three ports will outflow to the tub spout, the fixed, head, and the handheld. Some valves are all in one. They have the water volume ON/OFF, temp selector, and diverter all in one valve. Some manufacturers market them individually. You'll buy a supply valve that will give you ON/OFF and temperature selection, and the outflow from that supply valve will feed the IN port on the previously mentioned 4-port diverter. Do understand that when you shop, you'll be shopping for valve bodies AND valve trim kits. The valve body is a cast piece of brass that gets buried in the wall. The trim kit is the pretty (chrome, nickel, ORB, etc) piece that covers the hole in the wall and hides the valve body. In general, you buy them separately, but you need to make sure that the trim kit is compatible with the valve body. So, for the most part, you can either get: 1) the all-in-one valve body and then get a trim kit for that all-in-one valve OR 2) you can get the water supply (on/off/temp) valve body and a trim kit for that valve, and a diverter valve body and a trim kit for the diverter valve. Since you have a tub spout that you like, you'll probably want to get the shower valve trim kit(s) in from the same design group as the spout. Find that rim kit, then websites will usually contain links to find the valve body that fits the trim kit(s) you are looking at. Good luck!

We are on the verge of purchasing very well reviewed Sign of the Crab (Strom) plumbing products for a cast iron leg tub / shower converter fixture (riser, shower head, hand held shower head, leg tub diverter faucet...) for approximately $1,300 ..... BUT we just found something similar from Barclay, which is sold at Lowes and Home Depot, for about $400. The only reviews I have found of Barclay are about 7 positive to 5 negative, with the negatives all saying that a valve broke and there were no replacement parts available. Still, we could buy the whole set 3x over for the same price. But ... does the chrome peel etc? Anyone have experience with these Barclay plumbing fixtures? Thoughts?