The oil leak was coming from the the overdrive lever seal on the right side of the transmission. Never would have guessed such a small seal could leak so much. It didn't look that bad. The footpowder found it!

A couple of tips if you have to do the job.
- Bite the bullet and remove the transmission cover. This is to remove the operating valve so it doesn't fall in. I can't see how removing just the right side seal could leave enough play for it to drop but you never know.
- To get the ball bearing out of the operating valve, put a magnet on a screwdriver and put the screwdriver in the hole.
- To remove the operating valve, turn the overdrive on to raise the operating valve enough to grab it.
- The seal is easy to get out and replace. Slide a socket over the shaft to press it in evenly.
- The lever is pinned so the alignment shouldn't change and thus no need to adjust the overdrive.