My 97 Road King has three fender seat retention nuts.
One for the passenger pillion and two for the seat.
I have discovered that I have two different sizes installed for the seat (PO).
One fits correctly in the opening and has a 5/16 or larger mounting bolt.
One fits loosely and even spins a bit and it has a 1/4 mounting bolt.
I have also learned that this loose fitting nut is the one commonly sold as a replacement HD# 59768-97.
I am ASSUMING that I need HD# 7485 to match the correct fitting nut I currently have installed.
Am I correct in my thinking and is there a reason HD used different sizes?
Why isn't the larger retention nut easier to find?

 

To prove I'm not losing my mind. I found the correct seat nut at Ronnie's HD. The picture shows the difference in the new nuts (59768-97) and the correct size (7485) for my 97 RK.


retention nut difference

 

On my 98, The smaller 1/4" is on the back for the rear passenger seat, and the two larger ones are for the riders seat (2) both the same. 5/16"

 

Yes, 1 smaller and 2 larger are necessary

 

When I bought one it was HD# 59768-97. The base part is deeper than what the one you posted and looks more like the one on the right. Also its 1/4 thread