Welcome to the Forums and the World of Vintage Overlander ownership!
What you describe sounds like the trailer side of the Reese Dual Cam setup. The cam bars were typically clamped to the tongue, but in the early days of the system may have been welded to the tongue (I know of two 1960
Overlanders with the welded setup). I am attaching a photo of the Reese Dual Cam setup on my '78 Minuet. The hitch uses the Reese Trunion Hitch with standard weight distribution bars -- the standard chains are unbolted and replaced by steel saddles that ride in the stirrups on the coach -- you can also purchase new style bars that have a hook on the end that don"t require th saddles. The saddles and other parts are still available from Reese.
Good luck with your Overlander!