SPACERS, I am not familiar with 3rd gen trucks, but When you get your centramatics and put them on the hubs, when you go to put your aluminum wheel on the centramatic might hit the rim. (only in the front) If it hits they will send you a spacer about 1/8" thick that will go on between the centramatic and tire. They sent me 4 spacers and I only needed two, so I do have two in stock that I would donate to anyone if they needed them.
They also come in sets of a and b a for front b for rear, and they are a little different. On the 2nd gen, the rear balancers go on the front and vice versa.
As far as more stuff being stacked, I was concerned but it no longer concerns me, as things run real smooth.
I also had to grind the forge markings off my calipers. there was quite a thread on this in august of 05, that really discussed centramatics, that is when the group buy was running.