" I would have at least a FEW drips from my tranny when I park it. Nothing. Clean."
Not necessarily. I had a similar situation once a long time ago on a 66 Dodge Wagon. It lost a little fluid from time to time but I could not find the leak. I didn't let it bother me, I just checked the level and when it went low, I added some more fluid as needed.
I was in the Navy and while on a cruise, some gas station jockey convinced my wife that she needed to have the transmission rebuilt. He couldn’t find the leak but that was his answer. So she went to several shops to get quotes and second opinions, no one could find it so she took the best offer from an independent shop with a good reputation.
When I get back, the transmission still looses ATF from time to time, I’m out more money than I can afford and the guy who did the rebuild can’t figure it out. This one was difficult because the level would stay full for up to a month and then suddenly drop a half or full quart all at once.
I messed around with it on day in the yard. I parked it and let it idle in various parts of the yard so it was on different angles. After about an hour I was rewarded with a copious leak from the selector shaft seal. It would only leak if the car were at a particular angle, and then it really pumped out. It squirted out without leaving a trail on the transmission. No drips in the driveway because the driveway didn’t have the required angle. I put in a new selector shaft seal and it never leaked again.
I’m not saying that you have a bad selector shaft seal, but there are a number of seals that any one of which may leak only under certain circumstances, and those circumstances do not include being up on a lift. These can be very difficult to find and time is money. Mechanics usually are only allowed a few minutes of FREE analysis and they cannot always guarantee that even if you pay for hours of diagnostics, that they can find the problem.
If you are losing less than one quart of ATF per month, you most economical choice might be to just check the level on a regular and frequent schedule and top up as needed with the correct ATF. My Dodge had been loosing ATF, maybe a quart per month for many years before that gas jockey got involved. As long as I kept the level up, it wasn’t hurting the transmission and it did not need to be rebuilt. even the guy who did the rebuild tried to talk her out of it, but she had been scared into believing that it HAD to be done.