COUNTERBORE DIAMETER: 0.738 IN. NOMINAL; COUNTERBORE DEPTH: 0.688 IN. NOMINAL; EXTERNAL SPLINE DIAMETER: 1.028 IN. NOMINAL; INTERNAL SPLINE DIAMETER: 0.566 IN. NOMINAL; ACFT MODEL HU25A ATF3-6 ENGINE SCAVENGE AND LUBE PUMP ASSY; BORE SHAPE IS STRAIGHT AND SPLINED