My 99 GMC Diesel, old body style, currently has 33s that fit fine but doesn't have any kind of lift kit I can see (it does have cast lower control arms). I went to the parts house bought some shocks but they arn't long enough(shock bolt hole to bolt hole sitting on the ground is about 16" on the front). I was looking at some Rancho shocks, how do I know which ones to buy? All of the Rancho shocks listed for lifted vehicles had a rancho lift part number listed. It seems to me that I need a shock for a 4" lifted vehicle with stock mounting provisions, but they don't show a shock for like that?