what kind of shower valve?

wbatten

I have a shower valve (mounts in tub deck) that came with a used tub I baught off craigslist.
(1) I would like to know what brand it is?
(2) How the push button works on it? (does it have to be held down or does the water pressure keep it down?). Push button is spring loaded so it doesn't stay down. The push button activates a hand held shower wand on a metal hose. this valve was piped in between the tub faucet handles and the spicket (so water temp already adjusted before it gets to this valve). Both side intakes are the same pipe. Bottom went to spicket.

I would like to know if i can make this work without hooking it all up? valve's are expensive, worst case maybe i can buy new guts for it. I don't want to have to hold button down to shower.

Any help would be greatly appreciated.