yeah ive got the same problem with the fill plug on my rear diff.. and I found out I had a problem with it after I drained it ( smart, I know

) thinking about welding a nut to it but no experience with welding and a bit worried about the gas tank beeing so close, anyone know the safest way to weld near the tank? Im thinking about removing the tank, but dont know if thats a bit to much for just spot welding 1 bolt