I understand your problem. Your new truck has a new Reese hitch. So you need to replace your pinbox, so you can use the Reese hitch.
I would agree with the CW guys. Replace the pinbox with a new one. Removing a continuos welded capture plate will really screw up your pinbox. Grinding it off or torching it off. The old pinbox is not anything that I would want to use.
Your other option would be to mount your old SuperGlide hitch in your new truck. Probably will need to use your old frame mount brackets. Could be done in a few hours. Then you can use the capture plate, and will have a good automatic sliding hitch in your new truck. Sell the Reese. Or see if the dealer will allow you to return it for a refund.