On the end is a one way valve, some boosters use that type, that goes into a grommet in the booster. Most 4Runner boosters take a one way valve that goes inline, we usually take the line with valve from the donor rig.
I had the same issue when I swapped in an 80 booster. Toyota couldn't find me the part without a serial number... The diesel JDM 80 had a vacuum pump so it's serial number didn't help. The VW parts supplier had no problem supplying the needed check valve. Volvo and many others also use them. eBay has a slue of them... Doesn't help when you're driving around without one.