Narrow Rear End

Hello Wondering If Anybody Has A Home Made Jig To Cut And Reweld Rearend Housings? I Would Like To Do My Own This One Time And Need An Idea How To Set It Ture. I Know To Make Sure Of Square Cuts And Grind In A Downard Angle To Fill Gap With Weld Afterwards But Have Not Figured Out How To Ture It Before Welding It And It Not Costing Me Much. I Will Send Axles Out Anybody Know A Good Place To Deal With? Running A 8.8 Ford Axle. Thanks