I FINALLY got around to doing an oil change on my new (for me, anyway) '85 pick up, 318 engine. It needed it!! The oil was thick & filthy.

After crawking under the truck, I discovered why the oil was so dirty.

The oil pan drain bolt is ALL buggered up, rounded off, and quite solidly stuck.

Any/all wrenches and vice grips I can find will not budge this stuck, rounded off bolt.

What are my options here?

Can I center punch it into the pan,tap and thread an oversized one? If so, will the partial bolt inside the oil pan make some trouble?

Or should I find a used oil pan and swap it out?

Your thoughts and opinions, please.