Due to the design of the lower spring mounts, you can only safely add three 1/4" thick spacers below the coil spring. These spacers, available from Superlift, will net you approximately 1 to 1 1/4" of lift at the fender.
After adding spacers, don't forget to have the truck re-aligned. The installation of spacers alters the front-end geometry.
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Scott
sjbosso@mindspring.com