My dually started having a weird vibration I think its from the front at 40mph or so mostly at a cruise or decell situation and not so noticeable if at all when I'm accelerating. Any ideas? Thanks.

U-joints? Bad shock(s) would produce a bouncy ride like a old Caddy....

My truck is also very squeeky when going over bumps. I was using about 1/2 my weight and could push nose of truck up and down a few inches pretty easy, I think its just old shocks. I was just hoping to hear other people has similar symptoms.Thanks.

Then if thats so have both front tires check for balance and true... Then check the wheel bearings as well...

If the shock is seized or has a bent shaft it could. When I used to run RS9000's and I turned them up to "5" on the rear of a XCab SB chevy the truck would vibrate at certain speeds since the shock couldn't move fast enough for the road conditions. Probably not the cause, but I'm still throwing it out there.

Interesting AH64ID... I never had that happen... But I guess I learned something new today...

had the belt split on a rear tire and it gave a horrible vibration