Currently the largest Winn Putter grip would be the Winn Pro X 1.60" (WN0111).
If you are matching an older Winn putter grip then I would guess it to be the Winn Excel Jumbo Lite Pistol (WN0097, WN0120).
A couple of years ago Winn had the Excel Giant Pistol grip which was 1.65" but it is not longer available. It looked like this grip only larger. http://www.golfworks.com/product.asp_Q_pn_E_WN0043
Date published: 2016-01-25