If you work on older rusted vehicles, a high quality impact gun and air hammer are worth every penny. A shitty impact gun will take off like 60% of things, a high quality one will take off 90% of things. And for the final 10%, (likely in combination with torches and large breaker bars and impact gun) you can air hammer the living fuck out of the bolt or part for 15 minutes and it should help break apart some of the rust.

And for future self, a tube of anti-seize.

I questioned the need for my heavy equipment "fuck-you" sized impact gun when I bought it, but ive helped out more than a couple people remove old rusted on shit with it that their cheaper consumer impact gun simply couldn't handle.