JD model 71 flex planter (question about various tool bars)??

[pharmvet]

I have really been looking at various photos of the John Deere model 71 flex planters. It seems that they come in many different configurations and with many different options. Regarding the tool bars, I have seen some used with wide tool bars, more narrow tool bars and even some set up for the diamond configuration tool bar. What make a unit able to be used on a diamond tool bar? Can the part be purchased to make any of the units fit a diamond tool bar, or were they only made during certain years? thanks