wondering if anyone might know where I can find the vacuum diagram for a 99 b2500 2.5L.

some jerk thought it was funny to pour gasoline on my sons truck and start it on fire. got the fire put out before any real major damage but melted most of the plastic vacuum lines got all the front wiring replace along with the header panel, lights, hood etc. but I cant seem to find a diagram of the vacuum lines any help or suggestions please.