It's best to diagnose things before you pull them apart.

I used Raptor 2K bed liner aerosol by Upol,

Exact conditions when I purchased it: bad battery only pull started. Started up, a bit rough on idle, but otherwise is decent running order, put it into fwd and no sounds, put it into reverse, no sounds, fwd again and the squealing started with gas and forward motion between 3-8mph. It was unique enough and alarming enough that I figured it was a bad transmission bearing, like a bearing freezing and the shaft was rotating in the bearing. so I just decided to investigate for something obvious with that much noise. Found the previous owner probably hasn't changed the oil recently as the entire protective pan and drain plug were caked in with debris and dried stuff(Took me good 30-45 min to clear it out and find the drain plug). Oil didn't register on the dip stick, but did have oil in it. Was very black, but not burnt smelling or dirty with shavings. Just looked like it wasn't changed in a long time. When pulling the piston and cylinder, I expected worse, but the piston rings had obvious wear and carbon build up on the exhaust side of the piston rings and oil rings, but nothing was seized. All good questions to ask, but I'm very sure it wasn't a brake rotor, CV joint, or wheel bearing. Ive been studying the posting by MECH(thank you) on the design and operation. Makes me think that with this design, Honda knows the robustness of it, however the design uses the engine oil as the Hydraulic fluid for the Hondamatic unit. I would think this would be a concern for exactly my situation with lack of engine oil maintenance. However, the last section reads: " the Hondamatic is quiet, maintenance-free, rugged, impervious to external contaminants" So I'm not sure exactly how they keep it "impervious to external contaminants" if it's in the engine oil? I'm guessing they must be referring to other transmission belt transmission type technologies? Anyhow, all good thoughts, I still have to get the Hondamatic transmission out of the cases and look further/closer at it. I'll post my findings. if anyone has any diagnostic info aside from what's in the manual, I would appreciate the suggestions.

What makes you think it's a squeal from inside the cases ? Did you find any metal shavings or dust in the cases when you stripped it ? Could it be an engine mount squealing ? Exhaust rubbing ? Something like that.. I'd be really doubtful that anything inside there could be making a squealing, and under throttle, without there being signs of wear, and probably heat.