This is the weld:
The pinion bearing kind of feels a little too rough as well when you spin it kind of feels like some grit is in the bearing. So before I pulled the differential apart the noise was only made when driving in a straight line with a engine driven load and the noise stopped when the gears were in the neutral state and also when the wheels were back-driving the engine.
I was going to try to pull the pinion shaft off, which obviously the service manual says don't mess with it and especially don't mess with the pinion nut. Not sure I can get the pinion nut loose and I don't think I have a socket to fit it, I also have to get the seal off first. I could probably get it off with brute force but I would be trying to not mess up the seal if I don't have too. Seems like I almost need a very tiny bearing separator to get up in between the seal and pull it off.