One reason the 4.10/4.11 gears are scarce is the fact that a lot of us dirt track racers in the late 1970's scavenged them up to bolt into the 3/4 ton Chevy rear axles that were popular race options back then. The gears and axles were rugged enough to handle the power of a tight-winding small block Chevy engine making 500+ HP at 7,500 RPM and the rough surface of the dirt track. The earlier "full floater" Ford 3/4 ton rear ends from the 1940's got so scarce that a newer axle was needed and the Chevy axles were fairly common and not too expensive. A Muncie 4 speed with a 1.88:1 second gear working with a 4.10 rear end gear gave us a final drive ratio of 7.70:1, just right for coming off the turn at 3,000 RPM and winding up to 7,000+ down the straightaway. Do that twice a lap for 50 or 100 laps, and gears didn't last very long. We went through a BUNCH of ring and pinion sets!
Jerry
