I have looked a so many pictures, the center holes are a mystery.
After the '50s DeArmond came out with a lot of variations of the Model 2000 pickup; not so much the 'guts' of the pickup as well as the shape and style of the metal cover that dictated the way the pickup could be mounted.
The 'original' style was the surface mounted cover with the four screws at the corners of the flange, but because of the height of the cover they could not be mounted on instruments that had a rather low bridge profile.
During the early '60s Guild already used DeArmond 2000 pickups on some of their M-75 Aristocrat models that had a somewhat trimmed cover that allowed them to mount the pickup below the surface of the guitar top. One of those setups is pictured on page 71 of 'The Guild Guitar Book'.
Towards the end of the '60s Guild also mounted DeArmond pickups in mounting rings on a limited number of thinline archtop electrics that were already routed for a different style pickup. These mounting rings were slightly oversized simply to cover the 'original' pickup cavity.
Here's what this set up would look like:
The pickups posted by the OP could be this style of pickup, but that doesn't completely answer the question re. the DeArmond name, or in this case the absence of the DeArmond name on the backside of the pickups.
I've seen several different styles of DeArmond 2000 pickups without this marking on the back; I actually have a number of them in my possession. I have some ideas but right now I do not know exactly what period they are all from or whether or not they are from one specific period. Some of them I got in the big load of Guild parts that I got after the closure of the Westerly plant in 2001.
The pickups in the photo of the Starfire IV that I posted above did have the DeArmond marking on the back though!
Sincerely,
Hans Moust
www.guitarsgalore.nl