It's called sarcasm. Maybe you should learn to recognize it. And then maybe not take yourself so seriously?
Let me restate this yet again
"
These are facts:

My fullsize truck, that wasn't supposed to have a T56 from the factory, now has it.

Scored a USED T56 on craiglist and installed it.

FIVE years later, after much daily driving and spirited driving ( I haven't been nice to my T56), and some occasional towing, still going strong with no sign of failure. That's not good enough of course. Not space age technology......

You're the one with the labratory obviously, why don't we use that for your uber scientific analysis?"
I think you grossly misinterpreted my post. Some of that might not be your fault beacuse this deal is a lot like text messaging. There is no context when you're not talking face to face.
Ang again here we go copying and pasting: that is not the only time I have towed with the T56 since swapping it. It was the MOST RECENT instance. So get off the 100 odd miles of towing like it's the only towing this trans has done.
The reccommended service interval for the T56 staight from GM is to only ever top off the trans if needed, not to ever change the fluid. Myself? I change it every 5,000 - 10,000 miles. Does it need it? Probably not. But I have the peace of mind of knowing that for a few bucks in fluid the trans should live that much longer.
At the end of the day people like you will always nitpick some little trivial detail and try to blow the whole thing wide open, because you have nothing better to do.
I have said multiple multiple times: unfortunately the only data I have on this one is real world experience. By itself it's not the be all end all but it does give an indication of what you can realistically do in the real world. It is, one piece of the puzzle figuratively speaking.
Mr Plow speaks of a pump and cooler. AFAIK, he never used one, just commented to the effect like "hey if you're going to run a T56 in a 6,000 LB bus like my suburban, and you want to do towing regularly of things in the neighborhood of 13,000 LBS; a cooler and a pump would be a good idea". Not sure what gear he towed in, I'm assuming he made use of either of the double ODs.
Torque multiplication is key
. If you gear your axle properly to match the deep ratios of the T56 and the tall tires typical of trucks, you can tow anythign WITHIN REASON. Before I had the 4.88s I run now, I had 3.08s from when the truck was an auto, and with the T56 and 3.08s: you had to slip the clutch alot in 1st to get going, and 6th was all but useless, and forget about towing with those 3.08s cuz it's not happening.
The T56 is not a towrig transmission. Noone has tried to say it should be used in semis and 1 tons and combines. But it is a beefy trans that can hadle alot of what is thrown at it, if you're smart about it.
I drive at least 200 miles every week for my job, if not even more than that. It was a little over a month ago that I drug this truck back. So IF, something was hurt from towing, I think it would have already reared it's ugly head.