Thats not the rollers. Thats the slug sliders. When you pull the cotter pin out and slide the slug shafts out what you are left with is the "body" you refer to which is
http://www.murrays.com/50-61830000.htmlThats the axle the rollers are mounted to and it is installed by sliding it into the main traveler plate and rolling the edge down to permanently lock it in place. I see no way to remove it but by drilling it out and installing a new one. Only problem is I'm not sure the exact tool you use to roll the edge down. I'm sure I could do it but it would be kinda mangled.