Does anyone know what is is that keeps the vented lowers from fitting the 09 Road Glide. Has anyone installed these and what modifications were required. Thanks

 

The vented lowers are the same ones that come standard on the Ultra Classic. they fit Road King, Electra Glide and Street Glide models at least as far back as 99'.
On 2009 and older Road glides you need the Road glide specific fairing lowers. In 2010 Harley change the fairing mounting setup on the Road Glides to all the vented (more common) lowers to fit.
I believe making them fit on a 2010 bike involves changing the brackets that attach from the engine guard to the fairing and changing the front fairing mount.
It's a square metal tube that the wires run in between the neck and the fairing. You can see it easily if you look in and below your gauges.
It's a very doable mod.

 

close, wally, but no cigar. for 2010, the vented fairing lowers will fit. it is 09 and older that you have problems with. in order to make it work, you would have to change both the main fairing support, and the 2 fairing supports that mount to the crash bar.

you can also use some of the older vented fairings, but you have to trim the part on the cap that goes along the top of the crash bar. (this is of course, for 2010 and up).

there are several threads detailing what has to be done to change the older fairing mounts out to the new style. it is fairly inexpensive, but pretty labor intensive. you have to remove both the inner and outer fairing.

 

Change the fairing supports from the crash bar to the fairing to a pair of "invisible" supports from Hell's Foundry & you can use the vented lower fairings.http://www.hellsfoundry.com/fairing_support_fltr.htm

 

+1 on the hells foundry invisible supports! Helped a lot on mine with air coming under the fairing on my 05 also!