2000 D2 with 129,000 miles.
So I have been noticing some oil spots in the driveway, wife says transmission has been shifting weird/clunking, so I decided to check it out.

Under the hood and underneath you can see the passenger lower front side has transmission fluid on it. Took apart some of the plastic cowling to get a better look and it appears to be coming from the transmission cooler passenger side. Cleaned up the area with some brake spray, addressed the transmission (low fluid), and took it for test drive.
Transmission shifts okay, drove around a bit to see if leak would show and yes it did.
Under the transmission cooler on the passenger side red fluid showing up around the plug/sensor area (I'm guessing temperature sensor). So it appears to be the transmission cooler has a crack in it. Guess old age...

I have searched the forum but for some reason I cannot find much...

Has anyone had their's leak? Replaced it?
Go with new or used?

 

Not something that fails often. Did it take a hit from road debris? I'm wondering if maybe it is just leaking by the sensor or the fitting? I would say to look for a used one as new might be pricy but check it out.