SteelBender... take a look at the vacuum pump-TO-brake booster line at this link on our sponsor's WebSite:http://img.eautopartscatalog.com/live/N402074174OES.JPG
This is for a 1985 300SD... Q - What is your car... YR & model and how many miles ?

If you are talking about a "T" like the smaller one that is mid-way on this line, then I I would think seriously about using copper/brass fittings available in the plumbing department of your local hardware store... but before I would try that I would try and get a measure of just how brittle this old plastic line is. IF the plastic line is strong and NOT brittle, you might make repairs but if it's the other orifice tap that is near the right end of this line, then I think there is also a check valve in this fitting!

Also IF you do attempt this, do not restrict the line too much for it is IMPORTANT to have a full flow of vacuum to the brake booster!
Regards