What do I need to lock the rear and limited slip in the front of an 2004 Silverado. It looks like the rear is a 10bolt. Are they still 30 spline. What's the deal and the difficulty of installing one in the front of an IFS truck? This is for a friend. He was really upset when I sat him down and explained to him that he didn't have a 4wd truck just one wheel in the front and rear.