Apparently I don't know what I'm looking at . Your first pic looks like conventional differential gears ... Set of spider , and side gears . Side gears are usually spline'd to axle & retained by a large c clip . Grinding & welding doesn't sound like factory replacements . Like I said I'm not familiar with what's in Your pic. , But I hope that shaft and gear have splines , and the " weld " is just the end play retainer .
PS. ER70S6 and 6011 aren't really compatible to use on hardened parts like that shaft , and gear . Weld will probably brake .
. Good Luck .
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