63 Dodge Dart, now let me see;)

Looks like you have plenty enough wrap on the AC belt so it won't squeal being a single. I'm not sure if it's original to the truck, but my 88 D100 has a small alternator. Way smaller than what would have come on any 60's - 70's Mopars. I'm pretty sure it's a Denso alternator, but I will check when I get home Monday.