I know there are a LOT of posts about vacuum lines, but I've not seen a configuration quite like this. I've got THREE lines that go to nothing and the lower port on the intake was capped off. Here's a picture of what I'm looking at. It seems there is a whole lot missing! I just recently got her, so I haven't put her thru all of the paces yet, so I couldn't tell you if the 4x4 or cruise control works. Those are things I just haven't needed as of yet. (Being a manual transmission, I didn't plan on using the cruise control anyhow.) I could use some guidance here.

 

Follow the lines, and see where they go. Where they end up, will tell you where they should start.

 

You should have two check valves, one at the elbow on the intake and the other up buy where the ac lines are. The earlier years only had one. There was a tsb about this. In between the two(at the back of the intake) there is where the vac lines for the 4X4 actuator and cruise connect. Also the check valves have to be positioned correctly. They need to hold vacuum away from the tap on the intake. Check the cruise line they like to crack and cause vac leaks. There was some deviation on the vac lines from year to year. The factory really dropped the ball because there ain't squat in the service manual other than the two below.

 

Sorry it's taken so long to get back to this. Had kids drop by for a few days.😊So, I found that I had missed a line coming from the throttle body next to the MAP sensor that had been capped (well, somebody had stuck a bolt into it). Anyhow, going by the vacuum diagram (picture attached), I connected this line to the line coming from the Duty Cycle Purge Solenoid. That portion of the diagram doesn't look anything like what my configuration is in reality though. I don't see it connected to any part of the HVAC system, nor do I see any check valve on those lines and no portion of it goes through the firewall. I'm so confused!

As for the other lines... I left the line coming from the driver's side (under the battery) disconnected as it is part of the Cruise Control feature & I do not have any intention to use it at this time.

And, the last line coming from behind the engine (runs down and along top of transmission, etc.) I connected to a check valve and attached it to the lower Intake port. (I'll attach pictures of my low-tech handiwork. Don't knock it until YOU get stuck without the right size hose too! Just trying to make-do for the moment. &#128578

Does this look/sound right?

Edit: I did find two places where it looks like something MIGHT be able to go through the firewall. (attached pics too) But, they don't look right either. Still confused.😐

 

The one below the accumulator is a drain for the HVAC box in the cab. That one remains open, though some folks put an elbow on it.

The little one higher up on the firewall (bite me ralph nader) might be supposed to go to the vacuum reservoir....

 

First pic is only going to the t case. If you look at the (top)diagram in my last post that line should branch off at the back of the valve cover where there is a "T". It should continue to the second check valve(another "T") the reservoir then into the cab(#2 ).

Second pic is for the evap, It goes to the charcoal canister then the gas tank. It does not get connected with any of the other vac components.

The fifth pic shows where the reservoir line goes. I don't see any line coming out by the ac lines going into the cab so you will have investigate that. If you remove the radio i believe you can see the line where it goes out to the engine compartment.

 

Surprised no one has already asked: "What year & model?" Knowing can be helpful.

 

Vehicle Information
1998 Dodge RAM 1500 5.2L, Manual, 4x4
It's in the op's profile.