When I had my 7000 planter I modified my markers to have a cylinder on each arm . Only needed to buy the cylinders and added a homemade fasse valve to the planter tractor to get a third valve . That way I had  left and right individual marker control .
I also had added 7200 style notched blades with a heavy angle iron mounting for the angling of the blade .  And I made the square tubing heavier and made them flat fold at the same time .  Drilled the shear pin out to 3/8 . I think once in 2 years I broke the bent rod with the hole in it because after drilling it out it was thin on the outside part of the hole .

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planter modifcations 2011 015.jpg (286KB - 415 downloads)

planter modifcations 2011 006.jpg (430KB - 362 downloads)

planter modifcations 2011 009.jpg (149KB - 395 downloads)

planter modifcations 2011 010.jpg (229KB - 378 downloads)

planter modifcations 2011 011.jpg (276KB - 397 downloads)

planter modifcations 2011 011 (Medium).jpg (72KB - 315 downloads)

planter modifcations 2011 012.jpg (303KB - 364 downloads)