05 3500 6.6 Shifts Hard

[tholmber74]

I have a 2005 GMC 3500 Duramax. I am getting ready to take it into the shop but was looking for some insight on a few problems. I purchased the vehicle used with 37,000 miles, everything looked perfect. After about a month I found a Bullydog programmer under the back seat after doing research and understanding the capabilities of the programmer I had the bullydog outlook monitor installed to watch the EGT so as to not damage the turbo. Here's what going on..... 1) I find the truck will shift extremly hard into 3 gear or 4th gear. It depends on the acceleration, it almost feels like the rear end but I'm not sure. 2) The suspension seems to be much stiffer than what I think it should be but I could be wrong. I replaced all four shocks with Rancho RS9000's they are set on position 1 which is the softest setting but after looking at the rear supspension I see the the truck rides about an inch from the add leaf part of the suspension, in turn every time I hit a bump the suspension hits the add leaf which is like riding in a tank. This may be normal but I don't know since this is my first dually. 3) The airbag light is on all the time with a red light on the mirror for the onstar and no compass display "tried the power button for the compass". Just looking for some direction, thanks guys for your time. T in Atlanta.