Bullitt - do yourself a favor and run this test. Put the grapple on the tractor. Curl it down. Press the tines into the ground in this position. Then try to curl it more. Make sure it does not pop off the SSQA on the tractor.
I do not think you will have a problem as you have a vertical tine behind your Kubota SSQA plates, but there is an issue here that I ran into with my Markham/Gator grapple that it would pop off in this situation. On my grapple there is no tine behind the SSQA plate, so when you stress it, the grapple deflects/distorts and the Kubota plate has a "curl" in the top edge that has nothing to push against so it pops out. I added heavy angle as plates to act as stops and the problem disappeared.
It is not an issue with implements that have a solid face (like your bucket in the background), but anything open like the grapple can be a huge problem.
Green arrow points to the "good" tine that should help you. Red arrow points to the problem zone. Like I said, the tine should stop it, but it is easy to fix now, painful later....
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