I bought a 1977 Puch Newport that has a stripped transmission drain bolt. I've looked on Ebay, and Amazon, and in auto parts stores for an oversized piggyback drain plug to fix the leak but no one seems to have a plug this small (M8 threads, 10mm long, 13mm Hex head with slot).
Can anyone offer a practical solution to remedy this problem?; any help would be welcome.
Thank you.