I am running the 3/8 spacer with ome hd. After 30,000 miles like that my upper ball joints were shot...really shot and just switched to jba uca's. Lots of folks run the 1/4 inch spacer and you are only talking 3/16 more lift with the 3/8.... but keep in mind what you add up top comes off the bottom, so don't expect much down travel. It will be less than 2 inches, which means you fall into potholes. Also I have a plow mount and 2" receiver up front and little to no sag with the hd springs. Check the links in my sig for details.