The blocks are made of Dalron and will nor wear. I think Dalron is the correct name for the blocks. I'm going to visit with the local Chevy dealer and see if there is thicker rub blocks for the rear of the leaf packs. The clunking from the front curls is completely gone. That was where 99% of the noise was coming from. As I mentioned I am very happy with the fix so far.
2006 Seneca 35GS Dmax LBZ, Alli 6spd/ 4" turbo back/ Edge with Attitude/GPS/Bilsteins, air bags/Toyo steers and drivers, Counteract Bead balancing. Ford Ranger toad.