727 Help Please. pics!

That is the rear band pin that anchors the the band strut assembly.
There is 2 Orings on that and over time become hard and cause seepage.
They can be replaced in the car but are quite the chore to get back together.
I have seen guys take a chisel and break that aluminum retaining tab off the tail housing to get the pin out the make a bracket from the closest bolt to hold the pin back in. There is no pressure on the pin so a small piece of steel will do fine.
Now the trick is you need to remove the pan then look above the valve body to see the other end of the pin and tap it out with a bent screwdriver {home made tool) BUT !!! ONLY PUSH IT OUT ENOUGH TO GET THE NEW ORINGS ON or the strut assembly will drop. It will take some fiddling to get the pin back through the other side of the anchor but patience and time will prevail. Add a slight amount of silicone to the new Orings as well.