Need help finding a vacuum leak....

[KEP]

So I was reading late last night and came across a thread where someones 4wheel drive wouldn't lock in and the air would go from blowing to the exhaust....mine does the same thing but I wasn't aware of it until this morning. In that thread they said its a vacuum leak to the hubs. I've been poking around, following the lines I can see and I can't find any holes or connections not connected. Is there a better way or is there a "common fail" spot that someone can point me to? The gray line IS connected to that boot next to the ac condenser. Thanks for your help....this truck is going to be "fun" isn't it?

[Davey~do]

Did you check the vacuum lines where they attach to the axle? They generally dry-rot there and leak at that point. I'd try that first; then start checking to see if it's the vacuum solenoid.

[KEP]

Do I need to take the tires off for that? If not, I've checked everything going into the back and it looks pretty good. Where is that solenoid?

[Lilpooh]

Read post #5 of this link, lots of info.
heater problems and i have a baby that i need to take in my truck