What color primer are you using? I've had a lot of success with getting my paint jobber to tint light-colored primer to be a close match to the top coat color. In my decidedly biased opinion, two gallons for a cab/chassis job is a massive overkill. You should be able to do it with 3 quarts, or a gallon at most.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!