Need to repair/replace gearbox in 1996 F78 2.8l turbo diesel Fourtrack. Has done 305,000kms. Can anyone help with obtaining replacement gearbox input/4th gear shaft part no. 33311-87609/000? Any comments on experiences with replacing just the shaft in a box of this age. The case hardening is coming off the 4th gearwheel. Has anyone successfully re-case hardened such a gearwheel. I'm in Tasmania Australia so parts not easy to come by. Appreciate any learned comments. Tks in advance.