Belly grader for 1959 Case 310B

[lastchancegarage]

Has anyone ever heard/seen the belly grader option on a Case 310B? I picked up this backhoe and was told the extra set of valves was for a belly grader option. I went to the YT tractor site to see if anyone knew anything about the belly graders offered on the 310's but no one ever heard of that option. All the mount points appear to be factory installed. Even the extra three valves appear to be the same make and series as the loader ones. I'm trying to find any literature on how to hook this thing up. The backhoe is a quick release. The guy who sold it to my neighbor was tearing down a barn and actually still had the original eagle hitch 3 pt setup for the tractor! I'm just trying to find someone who may have actually dealt with one of these belly graders. Any info would be appreciated.
Here are some pictures.


I was told these curved arms were an option for tractors that came with the quick release backhoe. They're supposedly a heavier option than the regular 3 pt arms you could get without the backhoe.

[NNAATZ]

i have heard of them on a case, never seen one. i have seen simler set ups on 3000 and 4000 3cyl ford special utilty tractors