From pirate:
"This is one of those 'ask 100 people, get 100 different opinions" kind of questions. I'll leave it to you to sort through it and decide what you think is best. Personally, all my side and spider gears are welded to each other and the carrier.
Gears to gears and gears to carrier is the way I have seen hold. if you just weld the side gears and spider gears together all your force is on the pin. this may be ok on big axles like d60's, 70's, 14 bolt's, etc. but the pin can break when it is done like this on smaller axles.
I like to get some real beef in there. In the old days (before Everybody had a MIG) we would throw some nuts and bolts in the weld area and burn them in for additional filler. I prefer not to weld to the casting of the carrier, but I know people who have done it without problems.
If you have a DANA axle...weld the piss outta it...the new carriers are about $50-$75 new. The 14bolt carrier remains even if you buy a locker and they are $250 new...this is why people are only welding the spiders on the 14bolt. Just in case they go locker later....
The first time I helped a buddy weld one up, we welded it to the carrier and ended up having to reset the gears cuz the carrier musta expanded or something.
Well I can show you a way that has been tried and tested on front 44s and for 60s or any thing that you don't have to go in and pop out c-clips. Weld spiders to sides and sides to spiders on both sides and then take a rectangle piece of metal 3/8 thick or even thicker and drop it in on both sides and then weld it all the way around. Never has caused problems as of yet! 6 years going on 7."