Be aware that ball lock kegs and pin lock kegs have different thread sizes that the plugs tread onto. All told there were five thread sizes over a period of time, starting as small as 9/16, then getting larger, 19/32, 5/8, 11/16 & 3/4.
Here is a link that really helps identify which tanks have which threads.
By the way, I have brand new threaded for the nut & stem, disconnects 2 pin (gas) or 3 pin (liquid) for $7.50ea. New nut & stem pair $1.50ea in 1/4 or 5/16 barb size. Also have boxes full of tank plugs that were removed from old kegs.