Harley-Davidson Police Siren Pivot Shaft  (OEM #91233-59???)

There were at least 2 versions of this shaft-- a '55 and a '69.  But we're wondering if perhaps there was a third. 

This one looks like OEM #91233-59, but there are some fairly minor machining features that are slightly different compared to some NOS examples we've seen.  This specific shaft came from a Shovelhead era, rear-mounted siren assembly.  But a lot of these components may have been mixed and matched over the years.  We know it's not the '69 version, however, which was different.  So more research may be required.  

• Condition:  Used 
  
• Type:  Police Siren
  
• Vintage: 
  

050719  C-7  (19 01 27, 19-1)