Tow hitch pin size

Does anyone know the size for 2017 sr5 tow hitch pin? The one off my dads F250 does not work.

 

The factory hitch receiver on my '09 DCSB is, though spec'd by Toyota as a class III, as robustly constructed as the class IV hitch used on the Tundra. The outside of the receiver box where the pin passes through is very nearly 3" square; this of course means a lot of class III pins (many locking pins) will not be long enough.

The required pin is 5/8" diameter and must obviously have a "working length" of more than 3". This is just long enough for my OEM receiver, their will also fit as it has a 4" working length. will not fit as it's working length is too short...