Fitment is key, do not try and make up a large gap with a weld. If you don't know, ask! Lincoln has a hotline you can call about any welding related questions like settings. I should also post, none of those welds above are my own. Found those on car groups that I am in.
I watch videos like Haggard Garage and am shocked they haven't hurt someone welded the way they are. I don't think you need the most expensive tools to weld, but don't use a 90 amp machine to weld steering knuckles and control arms.Don't use a Flux Cored welder on a diff. It may work for a few events, or even a season, but if you're filming and having hundreds of thousands of views on a youtube channel. You should give out good information.