3a 2nd end thread class 16 1st end thread quantity per inch center flange, 3 mounting holes, 0.257 in min, 0.260 in.max dia, flow angle 9.0 deg anodize surface treated un 1st end thread series
2b 1st end thread class has 2 in. square flange in center w/4 0.281 in. dia holes 1.500 in. on centers cadmium surface treated unf 1st end thread series