The plot thickens...
Midniteblues opines that this is an early-in-the-run thing. My truck was born in Janesville and the vin would suggest that it was the 4977th off the line.
It's been awhile since I've been inside a column. I suppose my curiosity will get the best of me and I'll take it apart to see how it works. Soon as it gets warmer.
