drive train slack. ....seems excessive
 

sometimes when i take off quickly or accelerate aggresively, the truck gets caught up in a back-and-forth lurching motion. it seems like the engine and drive train are trying to catch up to each other due to the slack in drive components. it almost seems like if i took the crank shaft and was able to turn it by hand, it would turn almost half way around before the motion was transfered to the rear differential. ...where is this slack coming from? what would be the first components to check?

thanks in advance!

check you r u-joints first. see if there is any play in them. they are the first things to wear.

Matt