It's a 10 bolt carrier, really nothing special about it... Even if it fails then the parts are easily replaced.View attachment 654985
I think at $100. I would take my chances with a bought locker. Welding does not seem like a good option for long life and longevity even off road. I can see many issues with that method. Maybe demo derby but that's as far as I would trust it. I like things done right first time. Or not done at all. Happy Holidays. My M1009 off roads just fine. I am sure a few members can attest to that.
Your photo looks like a spool, which really isn't better or worse than welded. [based on my limited experience and knowledge]
Lastly, I'm planning an axle swap on this truck anyway. This is a great temp solution. I might decide to weld the next front axle also, depends.
I'm less of a fan of welded rears because they wear tires so quickly. A real locker [not to be confused with a spool] is obviously a much better solution. =D