If this is the vehicle with the vacuum ball that the OP cut the fittings
off the check valve is normally in the line coming off the manifold at
the rear of the intake. The line comes off the manifold through the
check valve and after the valve it gets split off 3-4 ways, One line
goes to the ball, one goes into the interior for the heat/AC controls,
one goes to the 4X4 switch on the transfer case and another goes to the
cruise control (if you have it). On the 94 I have the ball is about
twice the size of the ones in the later models. It is also mounted
behind the battery. On the later ones it is mounted to the hood on the
DS. I moved the one on the 02 and the 97 down to a spot on the heater
housing, shorter lines and it's out of the way now.

Besides I wanted that spot for the retractable trouble light!