It's not the stud size that causes the fit issue, but rather the backspacing of the wheel itself. The 2wd wheel uses a std GM rear drive backspace, the 4x4 uses a FWD type backspace, due to the wider track width of the axles. The reason for the extra width has to do with the independant front suspension used on them. You will be fine using the same wheel front and rear. One suggestion, if you want to keep the same nuts all around, have the flaps cross referrence the stud knurl to the same thread pitch that you have on the front. If you have to err on this, err to slightly larger knurl size, then simply install the new studs. That way, you won't have to have a mis-matched set of lugnuts.
