If you need a temp repair till you find a new line and you still have the broke off nipples what I did was I got a drill bit (the drilling end inside) that approximated the size of the hole in the nipple and I epoxied it back on. After it cured I carefully turned the drill with a pliers and that left the nipple attached. I did that to 2 of them.
Then I got some new longer vacuum Hose and carefully shoved that over the nipples. If you left it like that the nipples can still break off. So what you do is you Coat the section of the hole the nipple is in all the way back and round the plastic with epoxy and do that enough times to form kind of a Cast over the hose and the nipples and the plastic.
They you connect the hoses as you normally would. Later I replaced the plastic vacuum line with longer rubber hose and that allowed me to route the main vacuum line over the fender well better.
The other way is more complicated but more permanent. The hard plastic part contains a Check Valve for the Brake Booster.
You can buy generic check valves. Some I have have aluminum bodies and you can get brass fittings or other plastic/nylon fittings to replace the whole nipple section and cut off the old vacuum line and connect them with rubber vacuum hose. You could even use silicon vacuum line instead of the rubber one.
You can see the check valves on eBay. They are more frequently used on the suction side of fuel systems.
There is a picture in post #14. Back in 2007 when I did my first Oil Change I leaned on the line and broke off the little plastic nipples. The repair looks ugly but is still in use.
From slow start to no start. 82 300td
A pic in post number 5 off a generic check valve with an aluminum body.
Injection pump check valve