I specifically remember an old magazine article that showed a Dana 60 to be more efficient than an 8 3/4 mainly because of the ring & pinion orientation. Dana 60 is more centered. It also pointed out that a Ford 9" is the least efficient not only because of the R&P, but also because of the extra bearings. A GM 12 bolt was the most efficient of the "common" rears tested and I would guess that a 10 bolt would have been a bit better. In fact, I believe some rear end manufacturer had/has a 12 bolt gear drop-out made for Ford 9" rears with improved efficiency.

Granted, these differences were pretty small, but it apparently was worth the effort by several class racers who noted that they didn't see any loss of ET, especially after their cars had the weight adjusted back after the swap. Also worth noting, there would be less difference in weight if both were using a spool as opposed to a Sure-Grip or other such part. Added bonus is the durability.

I believed in it enough to replace the 8 3/4" in my Stock class Aspen Wagon with a Dana 60. I believe the weight difference was between 35-40 lbs,.Both had spools and star-flanged axles with the 8 3/4 being braced. The Dana had a thick, aluminum girdle cover. But I was mainly interested in durability as I doubt I'll ever have any breakage problems in a high-11 to mid-12 second car, despite it's 3,927 lb weight in K/SA. Unfortunately, with the problems I had, I was never able to establish a baseline to compare from and am currently trying to get an engine for it again.

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