At one time, there was a company, or someone, that made an adapter clip to do just that. You remove the spring clip on the pre-Rushmores, bolt this clip in and it provides the correct offset and threaded holes for the new style bags to fit. The support brackets are the same. A friend of mine bought them online and installed them on his 2010 Streetglide, I liked it so much I was going to put them on 2006 Streetglide, but alas, decided to buy a 2015… he has since passed away so I cannot ask him where he picked them up. They looked so simple, I asked myself, “why didn’t I think of that?” I will see if I can find anything on them, if they are even still around.
Here is a youtube video I found. Not the manufactured brackets I was looking for, but looks easy enough to modify the fronts to work.
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