Is it grease or gear oil?

[captain marty]

Am I making this too hard? My 28 has the worm gear rear end. OK, I see the drain and fill plugs on the rear end housing. The upper portion containing the worm gear has a grease fitting on the thrust bearing housing cap. Mine has a square headed plug. Now I would think a grease filling call for grease to be pumped in and I would think a plug is where gear oil is put in. What goes into the thrust bearing housing? Grease or gear oil?
Also I found raised letters on the left side of the gear housing: TT1 with an OD under the TT. Any idea what month this would make my 28?
Thanks,
Marty

[Hayslip]

Oil goes in the cap on the end of the worm. I've seen a grease fitting in that hole, but it's oil that is used to lubricate the bearing in back of that AA4190 cap. A grease fitting in that hole is not incorrect as it is shown in the 1929 Ford dealer brochure. The lube fitting is at 12:00, not 3:00, 6:00 or 9:00. Some caps have a larger lube hole with a plug. The markings on the housings TT1 etc are a mystery to me. I've only seen them on the right housing, not the left one. I'm guessing, but they may be to distinguish various casting molds. Ford used grease fittings on the steering box; again gear oil goes here too. A survey of 1928 AA owners worm housing markings might be of interest. Sincerely, Ed

[captain marty]

Thanks Ed:
I will put oil in that housing, I don't know how much to put in but I'm sure I will over do it. I think the TT1 on my differential housing is from the Model T era as I have read. I have only had this 28 for 11 years, I'm still learning.
Marty

[gunmetal]

My 1929 has a letter B raised letter. this stands for 5.14 to 1 gear in rear end. The TT1 I don't know. Good Luck