It took over an hour, with three different 7/16" wrenches of different sizes and thicknesses alternating between wrenches and each side of the engine, to get that problem nut tightened up, but it's done! There is a Snap-On tool (Part# AVPW716 and TMXK60) for this nut, and I plan to purchase that bad boy in case this backup alternator needs to come off in the (hopefully distant future.)
