I think I was thinking what you were thinking.

Maybe that was the intent of the thread title.

 

I got curious and since my '07 Softail Custom has the same motor I looked. Mine has a plastic clamp inserted in that hole that holds my brake hose/line in place.

 

Iz OK ... we were all thinking it ............................

 

Here's a photo.

 

..You back brake and line have fallen off. And what a nasty bike...Clean that girl once in a while. My old Softail has a few holes around like that. I took a rolled up paper funnel and used that and a rattle can flat black to make them disappear. Couple of them were on centered on the rear swing arm. Never have figured out what they are for. Harley has some chrome covers that stick on there but it's a pretty big tapped hole for that.

 

HD will sell you a plug to fill it $100.

 

That's $100 for the plastic one ... Stainless Steel is $250 ... But I advise the Titanium ... $850 ...