my tubes are plug welded...a 98 explorer 8.8. and I think, but not 100% sure, all are plug welded. if you look a the stangfix link/thread, he drilled these areas out.
one more comment...if you have a good means to cut square (you can rent a tube cutter from a rental shop), and can weld this is an easy way to get a narrow 8.8 with disc brakes, 31 spline axles with 5 lugs, which really opens up the wheels that you can use in your build.