Look at the difference in the back of the ebay rack from this in-service pic (magazine pic, left side photo of the two). If you zoom in, you can see what I'm talking about.
http://www.specialservicemustang.net...usmustang3.htm
Same design is shown here:
http://www.specialservicemustang.net/CHPatrolman2.htm
Those are the only two (good) shots that I know of, and they appear to be the same rack to me.
The rack I got from Robert awhile back isn't correct, just like the bracket for the whip. Nothing that a little modification won't correct, though. He does a nice job of restoring them, including the wiring.