I need help identifying this shower valve
This looks like you have a Single Valve Control Shower .. where yours has temperature settings on it. Maybe this is your tempering valve, it can also be a Pressure Balance Valve or what sometimes can be referred to as anti-scalding valves these valves prevent burns from water when say the toilet is flushed - all the cold water flows to the toilet and that leaves only hot for the shower hence you get scorched.

More and better pictures will be needed if you want to know brand and model information. 

BTW - the valve in the back might be part of the assembly and actually have the manufacturer model or info on it.