The Crown Zellerbach railroad was actually in Washington and I belive it lasted until the late 70's. They had electric locomotives that hauled flatcars around the facility. From what I understand the Columbia river would flood and submerge the flatcars on occasion. The flatcars were 24' and 30' with hand brakes. They had a hook style coupler with a large wood buffer under it. The arch bar trucks have 22" wheels on the smaller flats and 24" an the larger ones. Most of the truck parts have Lovestead casting marks on them.
At least 8 flats were purchased in about 1981 and are now spread around California on private railroads. There is one at the Nevada state museum also. I belive most everything else was scrapped.
Hope that helps.