Where is the fitting (fittings) located?
On later torque-tube trucks, a grease fitting near the top of the u-joint enclosure was used at the factory to put gear oil into the u-joint enclosure. On later trucks, the gear oil from the transmission will also eventually settle into the u-joint housing from the transmission (this might also be the case on earlier trucks).
People have speculated on why that fitting was installed/needed/used. Maybe for a quick leak-test on the u-joint housing? Maybe for a a quick "pre-fill" of a metered amount of gear oil into the u-joint housing, before filling the transmission?
If I have the correct sized pipe-plug available, I remove the fitting and plug the hole. I do not want anyone in the future mistakenly/unnecessarily putting chassis grease into the u-joint housing.
