Trunnion grease nipples.

[ferret76]

What size are the trunnion grease nipples? 1/4, 5/16?

[bmcecosse]

I would guess 1/4" - same as all others on the car - and any grease gun fits them!

[simmitc]

Unfortunately, over the years, different trunnion kits have been supplied with different size grease nipples. I've got four cars, two have one size, two have another. Nipples are not expensive, so buy a couple of each and see which fits. One thing that is certain: they are imperial threads, not metric ones!

[alanworland]

I think I might treat myself to some new ones as when I greased them a couple of weeks ago I think more leaked out than went in! This improved when the old trick of putting a piece of rag over the nipple was used, but they still weren't good!