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I walked to the shelf and measured mine at exactly 2" from the center of the mounting hole to the end of the 6-pin connector.

Hope this helps. 

I recently swappped out a drawbar on a new MTH Northern and discovered that under the plastic snap-on cover on the drawbar the length is printed in millimeters.    That length is measured from the centers of the holes at the ends.   For example a drawbar that measures a "hair" longer than 2 1/2 inches end to end is "officially" 45 mm hole-to-hole.     FWIW.