All right, I am a little confused here. I thought that the available Chevy rear spring lenghts were 52, 56 and 64 inches. I measured the ones on my 1970 Blazer and they check out at 52 inches on the nose. Then I measured the rear set on my 1999 Tahoe chassis ( my donor rig) and they come in at 54 inches. Are 54's called 56's or are they two seperate beast. I would like to use the longer springs with a flip shackle if possible.