"P.S. there is no part number or logo on the back visible - normal?"
I've never seen an Original NOS Ford one without one...
"There should be Ford part numbers and a FOMOCO (in a box) logo on the back side of all the pieces, except the lens, if it's original or NOS."
+1 I believe the same.
Yours having a Grey backing with no part number or Ford Logo is indeed interesting. It may be something that has never been documented. I would say more research should be done here..
In my personal experience, All the ones that I have ever seen that were original had the Ford Part Number and the Ford Logo molded into the top Plastic bar which is only visible if the part/dash cluster is removed from the car.
)
Tony K.