I don't mean to put down the folks that suggest air shocks, but air shocks and "load levelers"(coil-over shocks) are a VERY BAD IDEA for increasing payload capacity. Please understand that shock absorbers and the points they attach to were designed for dampening vibrations and bouncing but are NOT meant for or strong enough for supporting weight. Having said that, I realize that while some folks use them for a long time with no apparent problems, I have seen many shock mounts broken or severely damaged by them. The best and most safe way to accomplish your goal is to go with a product like the ones mentioned by "chuckthetruck"
Just my $.02
Gene
