It's time to order lift springs for my truck. I already have a 4" shackle flip for the rear as well as a 3" body lift. I'd like to be able to run 37s with the option of running 40s if I feel inclined to do so. I've heard 40s are possible on a first gen blazer/jimmy with 11" of lift. So here's the question: do I get 8" in front and 4" in back? Is the shackle flip close to 4"? I'd also like to get the axle relocation block but I don't mind if the back is a little higher; I just don't want the front higher. Also, I'd like to avoid using lift blocks. Another question: with the significant increase in weight on the front springs as a result of the big block, would it be best to go with a local spring manufacturer who can custom build a spring to my specifications? I was quoted $150/spring a while back and that doesn't seem too pricey for a custom spring. I'd like to go with National Springs but shipping costs are prohibitive. I'd appreciate any other suggestions anyone might have. 1970 GMC Jimmy 502HO/SM465/NP205 doesn't run just yet!