Here we have one pair of classic 'O' scale 2 rail freight car trucks by ACE. They are models of Roller Bearing trucks and are sprung with 8 springs per truck. They are stamped "1966" and feature rotating axle bearings.

These were recently assembled and came out of the original unopened packets. They are well sprung and would roll freely, except the rotating bearing caps need some run time to "wear in". These are impressive, robust metal trucks and insulated properly for 2 rail operation. They would be appropriate to mount on early express cars and other rolling stock that first used roller bearing trucks. 

These trucks will work out well for display or operation. They fit the old kit-built rolling stock quite well, and will adapt to Weaver models easily and add some heft to the plastic models.