Oh, and just to update, the leak seems to definitely be further back (towards the back of the car) than I thought. It's not leaking from around that area where the engine joins the transmission.

I'm thinking it might now be either that dipstick or a bad pan seal or something like that.

__________________
1983 300D - 314,640 miles (not all by me) - Daily Driver --Sold--
1983 300d - 215,000 miles (approximately)