I'm looking at BDS for my 1972 Blazer. I'm getting ready to put a Dana 60 and 14 FF under it from a CUCV. I'm wanting to run 35's and figured a 4" would be fine with the 1 ton axles. I've been reading all kinds of stories on here about using 2nd gen. rear springs. Some post says they're the same length (56" I think) So what would be the difference if not the length? Is it the center pin or bushing ilets? Do I use the zero rates? I have a double wall hard top that I use. So should I get a 4" and 6" rear?? I plan on putting a big block in it next spring (the rate I'm going, it will take that long for the suspension anyways). If I missed a good post throw the link in. I'm sure I missed one somewhere. I'm all /forums/images/graemlins/ears.gif on any information!