2a thread class right-hand 1.500" thread length hexagon head style 10 thread quantity per inch navy special project zinc surface treated unc thread series
3a thread class right-hand 1.375" thread length flat chamfer head style 0.061" hole diameter 20 thread quantity per inch cadmium surface treated unrf thread series
3b thread class 32 thread quantity per inch shoulder under 1st flange 0.090 in. minand 0.110 in. max thk passivate surface treated flange unf thread series
3a thread class right-hand 0.283" thread length hexagon head style 36 thread quantity per inch oxide screw surface treated without internal drive unjf thread series
Used on c-141 engine pylon. 3a thread class right-hand 0.359" thread length double hexagon head style 0.490" grip length 24 thread quantity per inch cadmium surface treated unjf thread series