marlincrawler.com, Allpro, and trail-gear are all based on Alcan Springs which are sweet. I have them and they flex better than any leaf I've ever seen. Deaver spring also is really good. As stated there are ways to build hybrid's like the chevy 63" or the ford F150 56" springs. for cost verses what you get the trail-gear 3" lift springs with some longer shackles are hard to beat. the Key is to not skimp on shocks as you will regret having nice spring not nice shocks. Use 14in travels up front and then make sure you do crossover steering and you will love the way it will preform. Good luck
sam