[Sharps40]

Put a wrench on the bolt head, a long one, brace it againt the frame or other sturdy component in the counterclockwise direction.

Put another wrench on the nut...add a cheater bar to this wrench, as long as will fit.

Get your hydrolic floor jack positionied under the long end of the wrench on the nut.

Make sure everything is ligned up and snug and slowly raise the jack, useing the weight of the thruck to undo the nut.

If it don't work, blow the bolt out with oxy torch and install spanky new bushings and bolts/nuts.

Good luck.