According to the -34P TM, the blazers and pickups use different valves.
GM Part # 25515635 for the M1009 and GM Part # 1257203 for the pickups.
21 PAOZZ 11862 25515635 VALVE,SAFETY RELIEF 1 UOC:209
21 PAOZZ 11862 1257203 VALVE,BRAKE 1 UOC:194,208,210,230,231,252,254,256
21 PAOZZ 11862 1257087...