i am having a hard time figuring out the vacuum lines on my truck. i have the diagrams from the autozone website,from under my hood, & from the Haynes manual but i am still having trouble. i have most of the lines connected but i can't find my HAC. are they on all of these trucks? if not what do i do with the lines coming of the carb.? i am just learning how to work on my truck so please, any help would be appreciated