That's the problem with dredging up ancient discussions...according to his profile he hasn't been here since December 2011, so the issue is probably moot.
It reminds me of oil pumps used on stock car racer rear axle. I don't think the alternator would enjoy the shock, vibration and dirt from a rear axle mounting. Also the alternator would have to run in a much larger range of speeds, from stopped to engine speed or even faster if there was overdrive. Increases un-sprung weight, a bad thing. I don't think I would ever do this!