Just put one in my 99 to replace the vacuum actuator. It's awesome to have absolute 4wd when I want. I don't think my actuator was bad but for some reason I don't have much manifold vacuum. I've checked and rechecked every possible point I could for leaks but found none. Just very low vacuum. I didn't put a gauge on to check to see just how much vacuum I had, but had very little at each and every point in the lines. Not that it matters at this point. Point is that if your 4wd sucks.........