My Kitchenaid SxS has also been very quiet. Pretty much the only noticeable noise it makes is when the internal ice maker dumps ice into the bin. But that's been deactivated since last fall, and frankly I don't miss the ice. I suppose I'll reactivate it once outdoor temps get toasty enough. Probably around June/July.
According to the sticker inside the fridge part, this model was made in December 2000. I probably purchased it in 2001. Still running strong.
As far as I can determine, and I had to use a cell phone to take a photo, it's Model # KSRS25IHSS02.
Bingo! Found the file for this fridge in one of my filing cabinets. I got the model number right. Apparently I paid $2109.60 for it, 22 years ago, including tax, delivery charges ($40), and extended warranty ($90). Whew!