Need Any Welding advice?

I was going to ask JUST one question, before all panties got in a wad!
Stepson has a big bass boat. Other day, he found the "bracket", yes it is big , that holds the BIG outboard, was cracked. It is cast aluminum. I also noticed that it is not just bolted together but some of it is welded.
Aluminum stock trailers are mig welded. What is the system to weld this cast aluminum? Just curious.
Typically you will need to heli arc it back together. For those type parts usually 4043 or 5356. When you hit it with heat if it has greenish tint use 5356 otherwise 4043. And you MUST preheat with a torch and grind out crack rounding all corners where grind groove meets OEM. I have weeded up a bunch of them this way.
Disclaimer: just a redneck welder