Achieving the ideal wear pattern on the ring gear requires shimming the face of the pinion gear at just the right distance from the axle centerline. Kwas says the S60 usually needs a shim between 0.010- to 0.025-inch thick. He installed a 0.015-inch shim as a starting point before sliding the pinion into the case.

The S60's main bearing caps are twice as thick as the caps on a standard Dana 60. They were torqued down to 85 lb-ft before finalizing the backlash and pinion depth.

Another benefit of the S60's adjuster nuts is that it offers a wider range of backlash adjustment. Kwas set it up at 0.005 inch.

The baseline 0.015-inch shim yielded a wear pattern that was a hair too close to the outside of the ring gear. Switching it out for a thicker 0.020-inch shim centered the pattern right up.

The S60 uses pre-loaded pinion bearing shims, which eliminates the need for a crush sleeve. After removing all free-play with an impact gun, all it takes is 20-25 lb/in to seat the pinion seal.

To ensure that the adjuster nuts and backlash stays put, the S60 features lock tabs that bolt to the main caps. Should the backlash ever need to be changed after installing the rearend in a car, it can easily be adjusted without disassembling the entire rearend.

Strange technicians etch their John Hancock and date of assembly into the ring gear of every rearend they build. It's just one example of the company's commitment to quality.

The S60's 3.150-inch axle housing ends are large enough to accommodate both the axle bearing and race inside the axle tube. This arrangement also allows anchoring the axles to the rearend housing using retainer plates. Not only does this prevent the axle from ejecting outward in the event of an axle failure, the retainer plate setup is less prone to leaking oil than a rearend that uses C-clip eliminators.

After applying a layer of silicone, Kwas bolted down the S60's handsome differential cover. Although it's ribbed for enhanced strength, since the S60 has such large main caps that experience little to no deflection under load, an integrated brace (to preload the caps) isn't necessary.

Compared to the S60, the factory 10-bolt originally equipped on Project Olds looks absolutely diminutive. The difference in the size of the centersections is quite revealing.

The S60 is equipped with control arm brackets, and spring and shock mounts that are compatible with '64-72 GM A-bodies. Since we already installed a Detroit Speed and Engineering coilover conversion kit on Project Olds, the coilover bracket had to be removed from the 10-bolt, and installed onto the S60. Afterward, the new rearend was spray painted black.

The previously installed DSE rear suspension kit and Baer disc brakes swapped over to the S60 without a hitch. Thanks go to Randy Johnson of D&Z Customs for turning the wrenches.

With the S60 anchored beneath the Cutlass, it was topped off with Lucas heavy-duty 85W-140 gear oil. To properly break in the new gears, Strange recommends allowing the rearend to cool after each 50-mile drive for the first 200 miles.

So we can drive around temporarily until the big-block and five-speed get dropped into place, we shortened up the stock driveshaft 1.5 inches and installed a set of 1350 U-joints.