I have very successfully used fittings like the ones in the link for years in vacuum setups. Not all are equal with some having very thin walls.

I got a bunch of "aquarium" fittings from this seller and found them all to have a nice thick wall which equals great for our vacuum.

For under $15 bucks I got enough fittings to fix 2 or 3 cars.

http://cgi.ebay.com/Air-Valve-Connector-Air-Line-Tubing-Aquarium-Tank-/400083971625?pt=LH_DefaultDomain_0&hash=item5d26dcee29

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1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."