3b 1st end thread class 12 1st end thread quantity per inch drill 0.5781 dia. hole thru left handside, tap 0.375-18 npt, drill no. 1 hole thru on top of tee, tap 0.3125-24 unf-3b cadmium surface treated un 1st end thread series
3b all ends thread class high purity aluminum, application of coating shall be per mil-c-83488, cl 3, ty 2, with 0.0005 max thk, chromate treatment shall be after glass bead peening at a max peen pressure of 25 psi unjf all ends thread series