Well, I almost jumped on this - but have a fairly long commute, so O/D is kind of a must for a dd. This seems to be an exception to the rule for 91s with 4L80Es. All others 91 8 lugs I've looked at have had the 4L80E (as you mentioned 95 S), and all the 90s have had a TH400, so this must've been either special ordered (if that was even possible) or a very very early production in the model year:
https://modesto.craigslist.org/cto/d...658482472.html
a different truck, a 95 K2500 with only 40K miles, slipped thru my hands by being a few hours late to call the seller last week - DOH! - there just don't seem to be many left that aren't trashed, have mega-high mileage, or something wacky going on. I thought the reg cab K2500s would be a bit more plentiful! They sure were when I was shopping for one in the mid-90s... Seriously looking for a 93-94 Reg cab long bed K2500 in a color that doesn't suck and with fairly low mileage - that kinda scratches all my itches.