Some alternators have a double groove pulley, while others might just have the single groove with an un-machined space where the second groove would usually be. Then there's a bunch of aftermarket pulleys available with a wide groove for farm equipment applications or adapting a old wide-belt stovebolt engine with an OEM generator to an alternator conversion. BTW, the pulley and the fan are separate units- - - -once the nut is removed, they can be separated, so any pulley you want can be added. All you need is an impact wrench. Friction alone drives the armature- - - -there's no keyway in the pulley or the shaft.

The adjuster bracket can fit on either side of the housing ear, but it might interfere with the fan if it's placed in front.
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!