Swap Meet Speedo

Anyone got any history on this speedo?

Found a deal at a swap meet.
Don't know what I'm going to do with it but it was too unusual to p*** on.

4-1/4" Diameter, 2592.9 miles total

 

It looks like a later Harley Davidson police special or after market Bikers Choice speedometer.

 

There was a thread on police car & cycle speedos? I thought they said the bike one is geared different than a car speedo? Not sure on that.

 

Any numbers on it? If not on the can look at the top dial under the inner bezel ring.

 

http://www.jalopyjournal.com/forum/showthread.php?t=397929

 

Ok- so from what I found out on the internet... Harley speedos from 1968-1980 were 1:1

 

Also- I found this:

http://www.ebay.ca/itm/2-1-POLICE-S...Accessories&hash=item3363032af7#ht_2070wt_952

which ids it as a