THE OIL SEAL ON MY JD 4200 IS LEAKING WHERE THE FRONT DRIVE SHAFT CONNECTS. WHAT SIZE IS THE NUT THAT HOLDS THE SEAL IN AND IS THERE A SPECIAL TOOL OR SOCKET TO LOOSEN IT? TRIED TO CHANGE IT ONCE AND GAVE UP BECAUSE I COULDN'T GET THE NUT LOOSE. IT IS INSIDE THE REAR TUBE ON THE BACK OF THE DIFFERENTIAL CASE. REGULAR SOCKET IS TO THICK TO GO INSIDE THE TUBE. ANY SUGGESTIONS WOULD BE APPRECIATED. DARYL