83 W123.
First, how to fix. The transmission cooler line at the passenger side of the engine is leaking at the clamp that holds it in place on the oil pan. Best I can tell, a rock hit the clamp just right and there's a small hole in the transmission cooling line. I can see where the line connects up at the radiator end. Where is the other end of this line (can't get car up today, at mom's) ? Is it removable by normal humans? Can I do it on jack stands?
Second: The fluid level is about 1/2 inch below low with the transmission a little warm. I am hoping this means I didn't yet burnt it out. It has been flaring more than usual and I think this is the problem. I'll drop the pan and change the fluid (converter too) to synthetic when doing the job.
Third: Can I clamp a piece of rubber hose here to control the leak? What kind of hose can stand up to this? Is this a very high pressure line.
Thanks for any advice.

I have not done this on a W123 but on a W108 it's not that big a deal to remove the line. Your best bet would be to find a good used line at a Pick & Pull. Forget the rubber line option that's asking for trouble. You might be able to splice the line together using compression fittings but I'm not sure the ones at Home Despot would fit a metric line. The last option would be to take the line to a hydraulic shop and see if they can repair it.

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Bill Reimels
Now down to one:
1972 300SE 3.5 W109 (Euro delivery)

It is not uncommon for those mounting clamps to wear a hole in the line. The plastic or rubber cushions give way and then there is metal-to-metal contact. If you need to drive the car a limited amount (ie: to get home) before making a permanent repair, I would suggest splitting a short piece of fuel hose, then clamping if over the hole with a small hose clamp. That should at least slow the leak to an acceptable level, if it does not stop it completely. Then monitor the ATF level closely.