Best 3/8 x 16 tap drill size
Irwin Tools 2634- 3 Piece High Carbon Steel - Tap 3/8" - 16 NCGEARWRENCH 3/8 x 16 NC Plug Tap - 388711NE-Z Lok 400-6 Threaded Insert, Brass, Knife Thread, 3/8"-16 Internal Threads, 0.625" Length (Pack of 10)Bosch CO2155 7/16 In. x 5-1/2 In. Cobalt Drill BitBig Gator Tools V-Tap Guide, Standard Sizes ...