the tubes are welded and it is a 8.5, but I pulled the axesl and they are 28 slpine, I called summit and to upgrade to 30 spline I have to replace bearings, carrier, and everything else inside to fit the bigger axels, it's going to cost around 1200 bucks and its still a 10 bolt, I am going to keep the ladders and buy the 9" its just going to take alot of OT to get there. Thanks you for all your comments. but I have one more question what do the ladder bars do exactally.