My guess is you have an early RMS suspension, they were indeed much wider, 1 1/2" I do believe, this was done to accommodate air ride, which put the hub to hub measurement at 61" if you contact rms, you can send your a-arms to them, and their shorten them up for you, and you'll end up with a hub to hub at about 58 1/2", that will fix you up just fine.