A quick search of the web shows at least 1 eBay seller
2ndgenautoparts (not mine) offering rebuild kits and related replacement parts for most if not all 216, 235 and 261 water pumps.
Also a whole lot more water pump kits for other Chevy and GMC engines that fall into our truck categories.
No indication where these parts are manufactured, but pictures don't display anything looking like junky or poor quality.
Would be interested in hearing about anyone's experience in doing their own rebuild with these parts.
Dan