I may be thinking of a different stem. Here we go. This was a prototype which probably resulted into your stem.
Not a completely unfair statement. This is the story told to me -
Between 86 and 89, Yeti wanted to offer framesets available with forks and stems, so they bought stems through Cook Bros. They in 89 they switched to the Evolution headset and CB didn't want to make a stem in that size.
Meanwhile, Frank was experimenting with and ultimately marketing products made from aluminum, including an alloy stem. I've heard the term "FTW Victory" stem but I'm not sure from where that came. Anyway, when Cook Bros said no to 1.25" stems, Yeti just decided to make their own and used FTW's stem design and simply made them out of steel. A legit "FTW Stem" would be an FTW product and thus made out of aluminum. The steel version would just be a Yeti stem.