In addition to location, i think the 7100 arms are different from the 7000 arms, the 7000 can have the automatic valuing that works off of the main up/down cylinder. The 7100 would need a different setup with the 3pt.
And, would it be a 4 row, 6 row, wide or narrow, or even bigger planter? The markers will be different lengths.
Its funny, when I read a message its easy to see what is left out - then when I write a message asking something I do the same thing, I can see what I'm talking about in my head, why can't everyone else? Funny. ;)