Strange Rear End Spools

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A spool permanently locks both axle shafts together so that both rear tires will always turn at the same speed. Many spools allow the use of larger axle splines which can provide tremendous increases in axle strength. The lighter, stronger alloy steel spool also improves ring and pinion life by providing a more rigid ring gear mounting. Many rear end problems are caused by deflection of stock cast-iron carriers or failure of differential side gears.