I am need help with a vacum system. I am pretty sure that the vacum lines have pin wholes or are crack.(Need replaced) I was wondering is the whole system run the air and a/c and 4x4 auto hubs? Cause the deforst does not work very well, and it takes a while to shift into 4x4 drive. This is a ranch truck that runs in the snow and mud all most year around, and was wondering if it was possiable to change the auto 4x4 hub shifting to some type of manual lock out hubs so that you know the 4wheel drive is in when you need it. I tried look up the lubs to change out but i didn't have any luck. I am sure it is on here but if some one could help with links that would be great.