A U-Channel truss like that won't do much to resist spinning a tube, which is why you weld them to the housing. It doesn't need to be an all around weld to serve the purpose of resisting tube twist. 4x 1" welds spaced 90° apart would be sufficient. Mine's fully welded all around without a truss, but a guy I work with builds rears for full body drag cars and charged me way to little, so it was a no-brainer for a "grinder" like me. Just make sure you do it right; high nickle wire or rod, pre and post heat, controlled cooling, preferably tig, but mig turned up hot can work if you know what you're doing. Often times you can hack it and it never becomes and issue. You'll be hard pressed to break it with a 4.0, unless it's a complete bind in the rocks while hammering on it in 4 low, and at that point the shock axle shaft would probably still be the weak link. The issue with the 8.8 is that the "plugs" are just welds to the unmolested tube. In other axles, it's a pin that's pressed into holes in both. Obviously better at resisting twist.