The stainless ones also have aluminum trigger guards and grip frames. I have one, though mine is
blackened stainless.
I'm pretty sure a friend used to own one that was all stainless, so I guess they changed. I've never been a fan of aluminum grip frames on Ruger and Colt single action revolvers, but I like the concept on what I call "pure utility" guns, and I consider the Bulldog to be in that genre.