I'm using the permanent magnet alternator spec'd in the Nuckolls architecture, manufactured by B&C Electric and sold as the "SD-8". The kit includes the SD-8, over-voltage protection, a 20 amp relay, regulator, capacitor and instructions. I installed it consistent with the instructions - horizontal on aluminum. (I spent a week of 1-2 hour sessions doing this 4x.) At the end, what you see below - scrap aluminum turned into a tray to hold the switchery of the aux alternator. Two rivet nuts in the aluminum plate catch 6-32 screws holding the red tray to the firewall. Using the tray allows me to horizontally mount the regulator on a cooling surface, and, of course, to do the connections at the bench. The big blue cylinder is a capacitor, included in the PM-8 kit sent from B&C. That plan was intended for lighter weight engines - think an O-235 in a Long EZ. With the cap the alternative alternator has a starting charge. If and as I had to hand prop the engine, I could switch to the auxiliary alternator and this cap would support the rectifier. There's not much reason to take it out, but it's not in the Nuckolls diagram and not something I'd do again. Nuckolls said not to worry about it - it certainly won't harm anything (so long as I don't lick the terminals!).