A lot of folks think those Hogue Monogrips were factory equipment because so many S&W revolver owners installed them. But they are NOT "factory" as the photo below will show that the Hogue Monogrip made for S&W bears S&W logos, not Hogue's, and they are the same shape on both sides so they don't cover the S&W trademark, as S&W revolvers can have the trademark on either side.
Some of them have the S&W logo in silver like the ones on the 5" 629-3 Classic DX in the bottom of this photo of three different variants of the Model 629.
But NONE of them have Hogue logos or high right sides that could cover the trademark. They are the same thing otherwise but you know how collectors want everything original.
Again, a lot of owners of guns with wood target stocks didn't find them comfortable and replaced them with a Monogrip, which is a very comfortable grip. Those wood stocks may not be comfortable but they look great on a gun and ones with nice wood figure like the set on the middle gun above bring big bucks these days as they haven't been made in some time. And those finger-groove "Combat" stocks like the ones under the middle gun are even more uncomfortable but go for $200 and more - if you can find them for a square-butt N-frame.
Here's a real odd fact. According to the third edition of the Standard Catalog of Smith & Wesson, a "bible" that every S&W enthusiast should own (you can buy it from Amazon), all 629 Classic hunters like Jeff's were round-butt guns shipped with the S&W Hogue Monogrip, so whoever changed them did so because S&W charged quite a bit more for the one with their logo on it and the person probably sold the original for more than the Hogue cost. Or something - however it happened, it did as the photos above prove.
By the way, I didn't research Model 29 Classic Hunters but I can tell you that only FOUR 629 Classic Hunters - all 629-1s - were made with the four-position silhouette front sight.
Ed