2a nut THREAD2a stud thread thread class right-hand nut threadright-hand stud thread 1.620" nut THREAD1.620" stud thread thread length 6.500" overall length 9 nut THREAD9 stud thread thread quantity per inch navy special project extension unthreaded on nut end 0.380 in. length with 0.720 in. dia. unc nut threadunc stud thread thread series