Dana 35-spline lightweight spool. (Stock Dana spline with 30° pressure angle.) This is interchangeable with the Summers manufactured spool. Fits 3.250" bore 57440 aluminum or 57470 nodular case. Uses 7/16" bolts. Manufactured from through hardened 4140 high strength steel, black oxide coated. 9 lbs. Installation - Service instructions can be found on Service Bulletin #0046.