My suggestion if you are buying used is to have the tow bar rebuilt before using it unless you know it's history. For example, I just had mine in to Blue Ox and they found the main knuckle worn out. They replaced it and rebuilt the entire assembly for $200. Good as new.
You also want to examine the welds on the base plate very close to see if there is any cracking or signs of failure.
IMHO, I would consider used/rebuilt tow bar etc but would spend a little more for a new baseplate.
Dennis & Carol
2003, 4006, 41' DutchStar,
Spartan, ISC 8.3L W/BanksPower - 2013 Honda CRV, BlueOx Baseplate, Aventa Bar & Patriot Brake. And the 04 Bird, Sunshine Car.