Just a guess #1 - Harley may have requested some "specials" be made for racing events, particularly trials, where you had to complete legs of the event within certain min/max times. Instead of the expensive "
enduro" equipment, these could be used with standard bikes. Larger diameter tires for dirt would make the bike go faster than the stock speedometer said, and the trials rider might break the minimum time.
Stewart-Warner calibrated civilian and police speedometers a little differently - at least on big twins. Civilian speedometers were calibrated to read a little faster than actual (so the driver thinks he's going 60 when he's really going 58), and police models a little slower (so the cop thinks you're going 58 when you're really going 60). If they did this on civilian K/XL models, for trials, the rider might break the maximum time.
Just a guess #2 - these were ordered for a limited number of police sales. Big twins had visually different civilian/Police units, but K/XLs didn't. So these might have been ordered with police calibration as above, or perhaps just to tighter tolerances.
Maybe these were for the
Eindhoven police, although I suspect those would have been KPH.
Your guess is as good as mine!
Dave