Im not sure what the little vent line is but you all you need to buy is one size line if you get a vaccum line t connectors from Autozone...They come in an assortment of sizes for like $3. I took my rear brake and diff lines and spliced them at the carburetor. Ran the big line off the Carb. to one of the smaller lines and ran them all in one to the front and used the smaller line that I cut up front. I took and spliced the front brakes and diff and the line from the back all together and just ran 2 lines. One small line and one 1/4 inch line up through the hole where the rack goes up. If you have any questions let me know and Ill try to get pictures.