I'm considering the Sundowner and found the 51540-06 which fits 06-14 locally, mine calls for the 51540-01A. With such similar part numbers and similar shape, is it worth driving across town to test fit on my bike? How different can they be?

 

It's just a slight revision, Probably something you can't even see... get either one.

 

Did you run the "fitment" tab?
It will give you the models that particular seat fits.
Try it for each one and see what you come up with.