Strange hop when pulling away up hill

[Mountain350]

Hi guys,

Last week I was on a fairly steep hill stopped at a light. When I accelerated away from the light, just after giving her the gas the whole truck jumped, almost like running over a 4x4.

It was such a hard bump I looked in the rearview to see what I had hit - but there wasn't anything there to hit.

The truck is new to me, with 23K miles on it. I got it from a Ford dealer where I have bought 4 trucks over the past few years. Its a 6.4 liter F360 with auto, short bed, SRW, extended cab, towing package. There was no weight (well, couple hundred pounds) in the bed, I was alone in the truck, headed home after work.

Any ideas? Should I just ignore it as a one-time event? OR does it mean I need to get Tranny work done? It was STRANGE feeling!

[1995psd]

were you pulling a trailer?

[Mountain350]

Just a hunk of granite and some sacks of mulch in back, a handfull of tools in the back seat.

It really hopped, thats for sure!

[sttstroke]

mine does it ever time i take off