use about a 1/8 inch drill....eyeball it from photo. Sending a pic of one our Pershings at Ft Jackson Museum. The coax did not poke out, it sat inside , so just put in the hole and if you put a light in it, place it back a bit. Disregard the Mickey Mouse skirts....some idiot at the shop put them on and they don't look anything like the real ones. [:'(]