GC Valve Question

How can I find out the PSI rating of a valve body if I have removed the solenoid? I have 7 GC valves and 1 Easystreet valve. I took them apart to clean and I noticed 3 of the GC valves are 300psi and 4 are 150psi. the easystreet valve is 300psi. I dont know why the previous owner has done what hes done but im trying to fix it all now. Any help would be appreciated thanks.