Nothing out my way for at least another 3 months....way too cold to be searching at the scrapyard. I did find one on ebay for a good price, but it is a variant of the model 400. :
https://www.ebay.ca/itm/Pintle-Hitch...ba50%7Ciid%3A1
It looks like something the airforce would have used. If you don't have any luck by spring I will check the milsurp yard.