The vacuum pump is gear driven. Look down where your power steering pump is and you will see a hose that goes back along the motor and up to the power brakes. That's the vacuum pump. Probably a vacuum leak if you don't have vacuum.
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Joe George
Eureka, CA
'95 2500 CC auto 4X4,3. 54,Combo EGT/boost guage,custom switch panel,PacBrake,TST #5,BD valve body,Automatic motorhome steps on both sides,Foldacover hard bed cover,Cummins chrome kit,Black steel grill guard,Front hitch receiver