3a all ends thread class ion vapor deposition (ivd) w/ thickness of 0.0005; 18 thds per in. first end, 20 thds per in. second end chromate surface treated unjf all ends thread series
3a 2nd end thread class 12 2nd end thread quantity per inch 2nd end bulkhead design, u/o cpv mark viii system passivate surface treated un 2nd end thread series
3a 2nd end thread class 12 1st end thread quantity per inch KC129C28; machined groove in flared end to accommodate seal ring per KC103 passivate outside surface treated un 1st end thread series
2a 2nd end thread class 12 1st end thread quantity per inch second end has a groove at end before threads passivate surface treated un 2nd end bulkhead thread series
