Slight Vibration

[huhner5]

I recently moved and was pulling around my 40ft enclosed gooseneck... Weighed about 12k lbs.... I was running my 100hp tow tune... I had to get on it hard one time coming on the freeway (on ramp) Ever since then i have a vibration(very noticable) only on the throttle while going 50mph and faster.... What might be the cause of this??? I looked under the rear of the truck and everything looks normal but something is definetly not right

[Vizsla]

You might of sheared the center bolt in the leaf spring, or snapped the pin off the block. It happens, and is not terribly uncommon.

[huhner5]

Thanks for the help... That is what i will check next