Dana 60 S60 or Ford 9"
I am building a 1968 Dart SS/AH chassis spec car, or rather close to spec for I could never afford to run this class but anyways I know they all like to run Ford 9" because they can change gears out much quicker. I don't plan on trying to change gears all the time, honestly, I may never change the gear ratio. I would just install a fresh set of gears in the car every couple seasons. Ford 9" are a lot more expensive to build for sure, which is why I am leaning towards the Strange Engineering Dana 60. I had a Strange Engineering Dana 60 in my tube chassis Challenger and after 7 seasons I had to put a fresh gear in it due to fatigue, which in my opinion is pretty good after 7 seasons of 950hp and 870 ft.lbs of torque. There was a chassis guy that gave me a hard time for running a Dana because he claimed it "twists" when under load. He was the only one I ever heard say that but I am always open to opinions/ learning new things. My new engine will make between 1,000 to 1,100 hp and car will weigh around 3,000. What do y'all think?
I too have just ordered an s60 from our Canadian Subsidiary Bears performance.
Strange has a good video on you tube showing that it is possible to change gear ratios on the s60 in 30 minutes because of the threaded adjusters. If you had previously dialed in a set of gears and know the pinion shim thickness for that gear set, you could swap
The gear set reasonably quick.
I have read this in a magazine for what that's worth, and that book
Claims that the Ford and the 8 3/4 mopar are what is called a banjo axle design which almost no oems use anymore, because this design is inherently weaker. The Ford gets much attention for its hypoid offset and 3 pinion bearing, but it has the same weakness as an 8 3/4 which is at the axle caps which are not supported by the casting
And axle tubes. The Dana as well as Chev 10, and 12 bolt as well as the Ford 8.8 are what is called a Salibury axle. This design supports the axle caps from flexing by capturing the differential bearings between the axle tubes. The caps can further be stiffened by a support cover as well. The s60 is also all nodular iron versus grey iron. A fabricator here locally tells me that a very specialized welder is required to properly weld the axles tubes to the cast iron/ grey iron centre section for maximum strength and no oil seepage at the welds. Strange uses this welding process on the s60.
The Dana also has the best hypoid offset.
The Dana s60 is only 15-20 lbs heavier than the 9 inch equal to equal. My vote goes to the s60.
A good friend of my ne has a 8.70 et Daytona with a Dana 60
After 2,000 passes all on the trans brake 727 torque flight, it finally broke a strange 35 spline axle. It broke right beside where the splines enter the spool. The splines inside the spool and the ring and pinion looked perfect. These are strong rear axles.
Your Dart should have no problem with an 8:50 et with a standard s60. IMHO