That is a Holmes 480 twin line wrecker body. The booms separate and can do side pulls. That is what the legs are for. They keep the truck from being rolled over while doing side pulls. It also has an add on wheel lift...something that was not available back in the 60's. It would be a cool truck to restore if it was in better shape.
I started out with a 74 C30 and Holmes 440.
On another note I saw this cluster for sale on e-bay
https://www.ebay.com/itm/263750303660?ul_noapp=true . I had one like this restored for my 63 c-10.