On my rear axle, it has two grease threaded caps to get grease to the outer wheel bearings. My mounting brackets for the shackles and bushings from the backing plate to the leaf spring are all missing, just holes in the bushings and tube styple brackets.
On my donor speedster project, it has three empty holes and one small brass flip up lid oil fitting.
Which would be correct for the 26/27 rear axle? Brass oil cups, or threaded grease caps?
26/27 use steel flip top oilers in the perches and springs. https://www.modeltford.com/item/3846.aspx For you project I'd use whatever will fit to get oil where it needs to be.
TO THE CREDIT CARD!!!!!
The shackles get oiled by small press in flip top cups on the perch and spring, the rear bearing gets greased by the cups on the axle with the screw off lids (steel).