What is the reason for the spacers? Are you going to maintain the original mounting pattern (5 x 4.75")? I take it that this may be related to your other post about suspension and lifting the truck. IIRC, the fronts have a different configuration than the rears (I don't recall specifically what is different) that limits what spacers will work on them. There are sub-forums (ex.: Wheels, Tires, & Brakes and Lifting) that have a lot of useful information about your inquiries. Also, you can type "wheel spacers" in the 'search community' bar at the top of the page. I think you'll find a lot of answers to you questions in the posts those referenced locations.