Since nobody else wants to tackle this one I'll throw in my 2 cents worth. You don't have a diverter, you have a tub filler, which may be a service sink faucet, and a shower valve above that has been piped around to a head at the other end. If you have illusions of brushed nickle or oil rubbed bronze or some such thing, that ain't gonna happen without tearing open the walls. You may be able to get new chrome trim for the shower valve, depending on exactly what it is. It is hard to see exactly what the tub filler is, but the best you are going to do is fake it with a service sink faucet (I am thinking Chicago here) that is polished chrome rather than rough chrome.
Maybe this will jar loose a couple extra comments for you.