I am selling a Dyna solo seat and bracket. It is in good condition, I took the cover off and added a piece of gel and re-riveted it. I ended up switching to a 2 up seat.
I'm not aware of one. I purchased my bike with this seat on it, what is shown is all that I had to remove. I do not and did not see a metal base plate with it.
I think the bracket brandon is referring to is actually on the seat/in the picture. Hard to see because the seat bottom is black and so is the bracket, but I had the same seat and can see it in the pic.