I got a 1990 W-250 pickup.The 4 wheel drive never worked on it when I bought it 2 years ago.I,m getting around to it now,tinkering with it. I suspected the front axle vacuum modulator on it.I took the old one off,put my hand vacuum pump on it and yes it did not work.I went and got a new one and installed it on the truck.Still no front wheels turning.The front shaft on the transfer case spins, but nothing turns on the axle.The truck is on jack stands in my shop. Does the truck have to be on the ground and rolling forward or back in order for the axle to engage once the transfer case lever is thrown in gear???? Or do I have little vacuum at the modulator? I put my finger on the end of the hose,there is some vacuum, but is it enough??? My next step is to pull the front axle cover off and see if the ring gear is stripped of teeth..If so,I have to pull the gits out of the axle.It is a Dana 44 FBJ. I,m havinh a lil hard time tryiong to find the special tool needed to remove the inner axle shaft. Chrysler number D-354-4 the tool and the adapter D-354-3.Any body know where I can get that at a reasonable price?????