Help identify mystery 32mm surplus Erfle

I have a 32mm Erfle eyepiece that appears to be identical to the one shown at
http://astrosurf.com/re/eyepiece_erfle_32mm_surplus_20020726.jpg

I haven't seen another one like it, anywhere online.
Anybody have any idea what it came from? I think it's military surplus, because it has a focusing provision for a crosshair reticle. It must be fairly recent (WW2 or newer) because it has coated optics. The thread on the helical focusing collar is non-metric, 32 threads per inch, which makes me think it's U.S. military surplus.

I've had mine for about 30 years but never got around to making the necessary adapters to attach it to a telescope. I have done so now, and I have to say I think it's one of my better eyepieces. Out of curiosity, I'd like to know what it came from.

Here are some photos of my example:

http://www.petealbrecht.com/eyepiece/eyepiece1.jpg
(Rubber eyeguard is from some other application, from Surplus Shed; I don't have one like the one shown at Astrosurf)

http://www.petealbrecht.com/eyepiece/eyepiece2.jpg
(With two threaded adapters I made to attach it to an old Zeiss Jena prism diagonal, M44 x 1 threads, probably prewar since it says only "Germany")

http://www.petealbrecht.com/eyepiece/eyepiece3.jpg
(Eyepiece, adapters, prism)

http://www.petealbrecht.com/eyepiece/eyepiece4.jpg
(With adapters screwed together to make straight-through 2" adapter).


Thanks in advance,

Pete

Attached Image:

Hi Pete,

Can you provide a photo of the markings on the back of the diagonal. I couldn't make these out from the pictures you provided.

Thanks!
Blake