Where to weld shim for Wain Roy coupler slop?

My TB175 has the typical sloppy bucket due to about a 1/4 inch gap between the bucket and the Wain Roy coupler. I hear people shim these to make them tighter? Seem's easy enough, just weld a pice of flat plate to take up the gap. Question is where does it go? On the top of the hook, bottom of the hook or on the bucket? Is there a needed about of clearence to be able to get the coupler into position on the bucket? Any input from someone who hase done this would be appreciated. Thanks everyone. Rich