Mig, no preheat. Just burned it it really hot and let it cool slowly in a welding blanket. Been welding diffs and knuckles this way for years, no issues. 3/16
Have you done anything with the shifters for the D300? I have cable shifters on mine and broke one of the cables yesterday so I wanted to see what you came up with.
lucky you, mine leaks like crazy but I have to put up with it as I have no money to buy an atlas. I might have to copy your idea with the seals in the shifter rails