Neat! That is a rare find. The cost of the brass meter was very expensive (and still is) and made it a rare item on the 2500 control valve. That thing is built like a M1 Abrams Tank and is easily serviced and maintained. All of the parts are still readily available, and that valve is still manufactured, though very few are sold nowadays. If you open the timer, you will see the date stamped on a white sticker next to the micro-switches.
Do you have a bypass? Most residential valves now have a bypass as an easy to install option. The 2500, 1500, 2700, 2750 did not have that and required a divertaflo or 3 valve bypass. The 2510 is a nearly identical valve, but in plastic and with a bypass option.