'95 P10 Auto Trans - Leaking from between engine/trans. Random nut in fluid pan

Hello folks. Posted this on the SR20 forums and got no replies so thinking I might post it here and test my luck. Just picked up a '95 P10 for $600 because the previous owner said it had a major transmission leak and they did't want to mess with it. Car wouldn't move when I went to pick it up, no fluid showing on the dipstick. Got it home, drained the fluid (which only filled a 10 quart drain pan 1/3 of the way...) and replaced the filter/gasket. There were some shavings in the pan but the car has 267k miles so I assume they were from normal wear. The odd thing though was a random 10mm nut/washer in the pan that had been sucked up by the magnets. I couldn't find where they went to so I put everything back together with a new filter and gasket and filled her up.

The car did go into gear, and I went through the proper procedure for when you replace the fluid. Took it for a drive around the block but when I got back home I found that it was still leaking quite heavily from between the engine and transmission. I have been told it could be the oil pump seal on the transmission. Sound correct?

Here's the nut/washer, any idea on this? (sorry about quality, tablet camera sucks)



The car: