its only a diff bracket, on thickish mild steel not a cromoly race chassis built to minimise material.
Preheating, rod hydrogen levels, mig gas choices, bracket jigs, etc etc may help but does anyone that you would pay really bother.
give the area a quick clean with a sandpaper rubberbacked flex disk on the angle grinder (the heat from this will drive away the water) align and tack IN PLACE with firm decent penetrative corner tacks all ends connected or simulated to ensure bind free linkages. (dry tacks defeat the purpose and may fail when it is too late and lift the corner. weld up to 1 1/2" at a time allow to cool to less than orange, weld the opposing side, wait and repeat a minute or so after orange goes. some residiual heat helps make the following welds quicker, better penetrated and therefore cooler. i prefer shorter bursts of higher current ensuring penetration especially where weld lapping is involved, and pushing a mig gives a narrower deeper weld whereas pulling is shallower and wider. vertical down often gives better penetration but can look more untidy if the pool drops, so pulse every 2 secs or so to stop the puddle running (slightly high current as described above)
why remove anything, it will only end in tears (warpage wise). if you remove the centre then weld the pumpkin you may risk warping as it is un supported and allowed to roam free, it will not warp with it in
airlockers (apart from the airline) are far enough away to be safe (unless you crank it and burn through 6 - 8mm metal (in which case who allowed you near a 3 phase welder in the first place
the only problems are where there is a 7+ mm gap to fill and you try to do it at once or get carried away repeating the beads (its hard not to i know)
also welding the head of a ht bolt to the diff may in time crack due to localised induced mixed metal stress, stress concentration from vastly different thickness as well as point loading especially in single shear. that is why there are normally shock brackets holding the pin in two places.
finally a broken linkage mount can kill if it lets go at speed, if unsure of skill level get someone else to do it.
weld in thongs - you will become a better welder quicker
