Is it different from any other K30 pickup master cylinder ?..
Is it plastic or cast iron ?..
If its the same as a civilian K30, I would think Dorman or some other aftermarket source will list one..if not a salvage yard is your next stop..
It is the cast iron,large master. Have had zero luck finding just the cap, gasket,yes. Cap no.Here is my M1028. Should be able to find one at any auto parts store.