I have the exact same leak on mine. In my case, it’s dark on the outside of the bell housing, but if you check behind the inspection plate, there’s fresh red fluid.
When I had the new motor installed a couple of years ago, it seemed like a good time to rebuild the transmission. After 4 return trips to the transmission shop, it still leaks and they never could figure out where it was coming from.
They used an aftermarket front seal from the rebuild kit. On the last trip, they finally replaced it with an OEM seal and it still leaks, so they basically washed their hands of it.
It’s not my DD anymore, so I decided to just live with it until I have the time and desire to remove it myself and figure out what’s going on with it.