*sigh.
I'll post this again, probably the umpteenththousand time. If you don't have a vacuum gauge in your cab, right there with your EGT, Oil Presure, and Water Temp gauges, your going to be speculating on what your problem is anytime you have a vaccum problem. If you have a gauge, then you know how much vacuum you usually have at any given moment, and you know how long it takes to pump it down to that level. Once you reach the point this poster has, now it's just a parts swap fest as you guess what went wrong. The little storage can is needed only on vehicles with AC and vacuum cruise. Trucks with neither don't have the can, so the vacuum pump will run the brake booster by itself, with no problem. You could run a hose from the booster to the pump directly, to rule out all that other crap as the source of your vacuum leak, but at the end of the day, you still won't know if it is your pump or booster without that damn gauge.