You could look into hell bent steel, I think rough country also sells them. As a matter of fact, someone is selling a set here in the forum. Have you already leveled the front? If so, what did you go with to do so?
Check this link. stangd1909 is the member that has them for sale.
Yeah I called Rough Country and they refused to sell me a pair separate from the combo kit they sell...I told them I did not need the other parts, just the coil spacers...They said can't do it...So IDK what would would do if you had the combo kit and something happened to one of the spacers...Guess you would have to buy the whole kit again as they are so hard on selling the whole kit...Was not impressed with their customer support...I also checked Hell Bents site and it seems they only carry front leveling kits