any auto parts store. In the US they sell it by the foot, buy about 1 and a half times or more of what you need. You just cut it to size.
Most Auto Parts Stores sell them.
You can buy a backpack vacuum from Amazon they have several listed.
Vacuum is created buy the pistons going to the bottom of the stroke and drawing air and fuel into cylinder. there is vacuum lines (rubber tubing) that goes to a canister which stores a vacuum for various systems to use without taking away from engine operation... your friendly neighbor hood Master GM tech
If you're talking about the air lines that force air into the exhaust manifolds from the air pump, that is an emissions thing. You could buy headers that have the threaded ports in them, add them yourself to headers that you've already bought, or defeat the emissions controls completely (not legal). Can't think of any vacuum lines involved with headers.
don't do this again...... Buy a repair manual! Buy a repair manual! Buy a repair manual! Buy a repair manual! Buy a repair manual! Buy a repair manual!
There's usually a sticker under the hood with one on it but if not, you'll have to buy a motor manual with one in it.
Generally vacuum lines are sold in bulk hose at any auto parts store. IF there are special ends, the parts store (assuming the countermaan is on the ball), should help you to make some. Auto parts store. napa, Autozone, etc...
You can buy a vacuum hose at the store that you purchased your vacuum. If they no longer sale them you can check sites like eBay and Amazon. These sites offer low prices because you can buy from the seller charging the lowest price with shipping.
Go and buy a good manual for your year and model truck. Sometimes, there is a vacuum diagram under your hood on a sticker
Wherever you can buy vacuum cleaners online, you can also buy accessories for those vacuum cleaners. Typically all you would need to do is do a search on vacuum cleaner accessories and you should find what you are looking for.
My best recommendation on where to buy a Hepa vacuum is Wal-Mart. They have some great deals, and even betterr prices! I found my Hepa vacuum there, and I use it almost daily.
One can buy cheap Numatic vacuum cleaners on websites such as Amazon and eBay. These vacuum cleaners can also be bought in stores at places such as Sears.