The Barnes 4wd Dana 35 differential cover is laser cut and formed in a state of the art CNC Press Break. The entire cover is made from 3/8" US Steel and we GUARANTEE THEM FOR LIFE. All covers are fully welded and machined flat and the threaded fill bung is TIG welded in place and the fill plug uses a 9/16 allen wrench. These covers are made to withstand the harshest conditions. Like all our products they are made in the USA.