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. Mounting hardware is included. Recommended hardware torque is 15 Ft-Lbs.