Testing vacuum booster?
 

Is there a way to test one without mounting it on the truck? Could you just put vacuum to it and see if there is a difference in force to move the rod? I have one that I want to put on my 71 but I want to see if it works before I go thru the trouble of mounting it.
ALSO, I have been researching prices on new ones. They show one for Bendix brakes and another for Delco. How can I tell which one I need since it did not originally have one?

I'l like to know that also. I'm going to be doing the same install.....

pull a vacuum on on it and see :gi: if it holds

I tested one like this. I just used one of my cars that have power brakes and pluged the check valve into the test booster. Start car and test by pushing the brake rod in to simulate putting the brakes on. If it goes in easily, it's working. I also tested it by shutting off the car and waiting about 1 minute. Then pull check valve. If there is still vacuum, you've got a good one. :)

Bob