One of the outlets need a rubber hose going to a intake manifold outlet usualy at the base of the carb., the other is a release outlet, trying both outlets in the wiper motor will tell you which one it is..Vacuum wipers on a good day had their problems and on a bad day , well they didnt work at all..Have you tried using Rain-X on your windshield, I know thats what I ended up doing once the wipers on my ride let me down too many times...Hope this helps my friend...