That lower bolt that attaches the alternator to the engine mount bracket with the four nuts, can be a PITA.
I had to remove the bracket off the engine block with the alternator. I couldn`t turn the bolt, and the alt. would hardly move at all. I soaked the bolt in PB Blaster for over a week. used my air impact on it, and it would turn but not come out.
finally bought a smaller diameter bolt same length, and beat the snott out of it with a large hammer. since it hangs down so low, I guess all the salt, road grime etc... over the years rusted the bolt to the aluminium.
The rust actually swells up and makes it tighter.
when I used the new bolt, I slathered it up with anti-seiz compound. great stuff, use it on everything
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one thing I noted after I got the bolt out, the PB Blaster only penitrated about 1/4 inch.
Note: I should add here, I had pulled the engine which made it easier to remove said bracket. I used the inpact after I removed it. I soaked the PB stuff when I had it sitting upright, w/o much penitration.
It is bolt #2 in the below post.
Charlie