Beginning in 04 the VR was most certainly proprietary as BD had a company making them for BD.
Beginning in 05 the entire charging system became proprietary as they began using the smaller rotor and having protrusions fabricated into the primary case to prevent a standard size rotor and stator from being utilized. They also began using a stator with more coils. I am sure it was all in an effort to support what they we're doing with their electronics but it was in fact a detriment. One of the reasons so many shops have issues with doing Big Dog work is because they believe, as global statement, what was stated earlier here "The charging system and vr are definitely not proprietary, a vr from Harley along with stator is the same as an evo". In theory that statement is correct. In reality, for Big Dog, it could not be further from the truth if you want to maintain your BD at optimum levels with their OEM style system. Not everyone wants to do that but we, Wild Steed Worx, believe BD was on the right track they were just going about it the wrong way. If your EHC, or other components, received damage due to the old charging system and you then install a new charging system to prevent further damage is does not mean that now everything is safe. Anything that received damage previously is still damaged and may liekly fail sooner or later. I deal with this on a daily basis talking to both private customers and shops. As I have stated previously in a number of posts the first thing that needs to go on a BD, provided it is OEM and in some cases if someone has installed something that should not have been installed, is the charging system. To date the only two VRs I would ever think of installing in mine or any of my customer's BDs is a CompUFire, my first preference, or a Cycle Electric. Both are U.S. made and have a long history of success.