it seems that like the 4x4 are really having a problem spinning from a stop and i can understand that they are heavy as he!! and add on the 20's they are huge! now in my case i have a 02 dodge ram 2wd long bed with the 4.7 and no LSD with 3.55 gears and the 17 inch wheels, and mine will spin the right rear with no problem on dry pavement and on wet forget it i dont even have to try and it does it, now im gonna go off on a limb here, yes the long beds are heavier than the short beds but maybe because my truck is longer theirs not a much right on top of it as the short beds, but then my drive shaft is long as anything and is a three piece with a carrier bearing to support it, so more to turn. my truck from the factory weights 4900#'s and then add all the liquids and then me, they are big machines.

 

2004 1500 4.7 QC Short Bed 3.55 Anti-Spin 2WD. From a dead stop can get a little spin out of the tires 265/60/R18. With a little breaking I can light them up. Add-ons CIA and a flowmaster exhaust.