This steel spool fits 7.5” GM rears using 28 spline Ford axles or 28 spline GM axles with C-Clip eliminators. Reduces rotating and unsprung weight. Customer must determine if they have thick or thin ring gear. 29409=8.75 lbs. / 29410=9.7 lbs. Ratios 2:73 Thru 3.08 Thick Gears / 3:28 Thru 4:56 Thin Gears