Most "late model" Waggy axles had 2.??:1 gears. Either ways, yes you need to regear. Most of us go to 5.14, some go to 4.88, and an even smaller percentage to 4.54/4.63. Still others, who swap out both axles, go 5.38. Both axles need geared the same. As far as bolt on or weld on. There is no such thing as bolt on. There is welding involved. The closest thing to "bolt on", would be staying spring under axle w/the waggy axle, and limiting tire size to no larger than a 35" (which depending on your setup, may or may not be a tight fit).