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Chrysler used two driveshaft yokes: the small Spicer 7260 U-joint (left) was reserved for grocery-getters, while the larger Spicer 7290 U-joint (right) was used with factory 440 and Hemi muscle cars. Ironically, our weak-kneed 741-case Sure Grip centersection came with the big 7290 yoke, while the boy-racer 489-case spool came with the small 7260 yoke, so we swapped them. Generally speaking, Chrysler 741 and 742 pinion gears featured 10 splines (aka coarse spline), while 489 cases use a 29-spline yoke (aka fine spline). This is another way of saying most 489 cases came from Chrysler with a fine-spline yoke. Fear-mongers claim the stock strap-style U-joint retainers are too weak for race duty and should be replaced with U-bolts. Don’t tell that to Mr. Norm, whose blown, fuel, Hemi-powered Grand-Spaulding Dodge ’65 Coronet exhibition-match racer ran high 8s with the straps.