Vacuum line's purpose?
 

Am I correct in assuming the small vacuum line that attaches at the rear of the intake manifold,(LS6 style) is the line that goes to the air pump? I've removed the pump and it's nest of snakes, but I'm wondering should I plug the line right at the intake manifold outlet? BTW, this is on a 'vette, but it's probably the same for f-bods.

That vacuum line is for your HVAC controls. So if you want to use your vents for anything, I'd keep it.

There is a vacuum line for the AIR setup; if you removed your AIR and have an unattached vacuum line from it, you need to plug it. At least that's how it is for f-bods.