They're mostly for trailer queens whose only mileage is clocked driving in and out of an enclosed trailer at a car show. That's a long way from the real world of a daily driver. Fairly recently, reasonably-priced conversions of the 10 SI internal-regulated alternator have become available in both positive and negative ground 6 volt versions. That's a good thing for the people who want the reliability of an alternator without having to go through the expense and effort of a 12 volt conversion just to have an alternator.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!