"STEEL ALLOY COMP. 4140 PER QQ-S-624; ALLISON ALTERNATE MATERIAL STEEL SAE-4140; HEAT TREATMENT QUENCH AND TEMPER TO ROCKWELL ""C"" 32-36 PER 8355700; OD 17.462 IN. MIN TO 17.466 IN. MAX; INNER BORE DIA 16.260 IN. MIN TO 16.290 IN. MAX; BOTTOM WALL THK 0.240 IN. MIN TO 0.300 IN. MAX"