can someone explain to me what each of these two vacuum ports behind the tps are for? I was thinking of using the larger diameter one for the vacuum line for my truck's master cylinder/powerbrakes any thoughts guys? is it a vacuum fitting? I'm not running any sort of emission stuff so thats not a consideration

 

one goes to the valve cover and the other goes to the vacuum canister, I think the top one goes to the valve cover breather and the bottom one goes to the vacuum canister.


EDIT:
http://www.mrgasket.com/accelpdf/ChevyLT1.pdf
this sit ehas some info, I can only find indication for one of the barbs, I know one of my side ones goes to the vacuum but I have some minute problems with that line that I am working out, hopefully somebody else knows so I can properly route it, pictures would be cool too