IIRC, there are only a couple of vac ports on the pside of the carb. One is the line to acutate the secondary throttle plate, and the other is the aux accel valve which squirts fuel to the secondary barrel (again, IIRC).

I'd download the fsm from MontyMcV's site to get the vac diagram, which is rather confusing.

Several of the vac lines only have vac when the engine is warmed up (they go thru the thermo vac valve on the water neck, the black plastic thing), and others are ported vac, where the vac port in the carb barrel is above the throttle plate rather than below it, and only see vac when the throttle is opened past the port (see the diagram). You need to know if your truck is Kali or federal, and whether or not it's got the high altitude junk.