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I believe the 741/742 have the same (very desireable) clutch sure grip unit itself which'll interchange w all 3 (including the 489 which OE has a cone sure grip). 4 diff pinion flanges 2&1/8 2&5/8 10 spline 29 spline




RR the 741 spanned both the 742 era and the 489 era , those made before 69 had the clutch type , those made 69 up were cone ...