This Is No Arbitrary Modification...
... as Paul has already suggested, you should just let it be, unless you see some cracking or other indications of metal fatigue.
But if you must remove and replace the coupler, it would be good to upgrade to 2 5/16"
Make sure you are dealing with a certified welder as it involves cutting the old coupler off and welding the new one on.
2007 Classic Limited 30 (Sold)
2007Chevy Silverado 2500 HD Duramax/Allison
Four Corners Unit WBCCI #8654, Affiliate NM Unit