International 9900 frame slope issue

[CraigW]

Hi, I'm new to the forum, and was hoping to get an answer to a problem of frame slope. I've recently purchased a 2011 International 9900i, and once put to work(under load), I noticed driveline vibration, and immediately checked the height control valve for proper setting. It was set approx. 2 inches below my Hendrickson HAS 460 specs. Problem is... once I set the height to 4 3/8" empty or 4 1/4" loaded, my frame slope is WAY off! Instead of near 0 degree frame slope, I have approx. 0.25" drop forward per foot. Making me believe the front axle blocks are about 4" too short. I've tried calling International, and can't get any answers. Does anyone have experience with Hendrickson HAS 460 suspensions, and have encountered this problem?