sw corner ia.
very simple: new kinze on one side, new case on the other. no special tools, bolts straight on. dirt never builds up between openers like the red ones I had would do several times a day, and these will not pull sideways. makes a very pronounced and narrow V seed slot without the stupid frog thing the red ones have to have.
works through the heaviest of cornstalks without plugging, can cut anything you drive through.
I have no idea why these aren't made this way from the factory.