That is what it means to me.
While this piece of information does not pertain to your year truck, it might be of interest: GM filled the SM420 4-speed transmission at the factory (in at least some years, 1947-1954) through a grease fitting near the top of the transmission assembly.
Also the Shop Manual instructions for refilling that SM420 transmission, was something like: "after draining the transmission oil, fill with new oil to within 1/2" of the fill hole on the upper side of the transmission".
