I have run the same mudflap on all my FX style bikes; I just remove it when it's time to sell. I like a nice,clean unmolested undercarriage. I also ran flaps on both of my Corvettes, much to the disgust of my Vette buddies...they protect the paint from rock dings. I am a big believer in flaps.
What I could never understand, was a mudflap on the rear fender. I mean...what would be the purpose?
Here is a pic of my '90 FXSTC & the chick I still live with(my ex), from 20 years ago. You can see the flap on the front fender. I still have it, but don't run it 'cause I have an FL fender now. It has been on several of my bikes, & will be on my next FX bike.
BTW please don't goof on my "Live To Ride" A/C cover. It was cool back then, & looked really great.