[Chaplain]

I did a search and couldn't find anything. My question is, is there any special procedure for welding on a differential that is off the car? It seems I read or saw one time that it is possible for an arc to jump inside of an assembly, doing damage to a bearing or gear mating surface etc. I want to weld on the brake line tabs and was wondering if I need to dis-assemble the entire rear end first.
Thank you in advance for any advice.