1982 300SD Alternator Pivot Bolt won't unscrew!
This is a thread I started when I had the same problem. I'd take car to a muffler shop and see if they can get some heat on it and get it loose for you like I did unsucessfully.
The guy I used got some heat on it but I still had to soak it in penetrating oil since he gave up on it. I soaked it 3 days after he was unable to get it out but he did get it to turn 3Turns CCW.
I read the other responses here also. They may work also.
I can tell you that I far exceeded the force I figured would break the bolt but it finally came out. You may see it is cross threaded like mine was but I was able to reuse with some anti-seeze put on it. I used a 8" box wrench with a 2 foot cheater.
Get some really good rust buster. I use the stuff sold in CarQuest. Let us know how U make out. I know it is very frustrating.