The "A" on the end of the part number...
Seriously, I am not sure - I have the 52093-08 on my 2008 FLHTP...
basically, the "A" on the end means it's a newer revision part, and probably had some changes made (what changes, I don't know... could be very smaill)...
when in doubt, I would go with the latest and greatest revision part number, unless you are getting a really great deal on the older revision number.