Hey, Markham has forks too. I just got a tooth bar from them. It is really nice and heavy. I had them put 8 teeth on it. The flat bar I was referring to is the design that Markham's uses. 1 flat bar attaches to all the teeth and the teeth themselves hook over the cutting edge of the bucket. On the EZattach design, they use a V shaped piece of steel that hooks over the cutting edge.
Wow, you got the big tractor, don't you. How big is the bucket on that thing? Sounds like that you have a bolted on cutting edge, where as mine is welded on. You might have to take a picture of that thing before you order anything. I know that some of the V designs fit over the bolts, but I think you would be better off getting a toothbar that fits the bolt holes. I bet Markham's could tell you how to do a template so the bolts line up correctly.
I am calling Markham's to see about some forks. I was real happy with their service and product.