What ist this????
 

Hi everybody, the new owner of my 1979 Rivi found this (see pictures), something I haven't seen before. He thinks gearbox oil is leaking from there. What do you think? Thanks for your help!
https://cimg3.ibsrv.net/gimg/www.bui...cad3911efb.jpg
https://cimg4.ibsrv.net/gimg/www.bui...75a0a26805.jpg