I have had a number (approximately a dozen) of these (122-key terminal boards, that is) pass through my hands, and the label always said "Model M" or "Model F" (if there was a label present).
The smaller Model Fs (XT and AT) that I have owned did not have labels on the outside, but they were located on the interior metal plate.
I am surprised to see a label that has the usual "other" information without saying what the actual model is, but then I have never owned a Lexmark terminal, only IBMs.
Verification of the metal back always indicating an F would be helpful. My guess is that is accurate, but I could say for certain. The wikis do not address the case construction issue, as far as I can see. We know that the F AT had plastic shell case top and bottom, and probably many of those "weird" specialty boards, too, but there is surprisingly little discussion/information of the big boys compared to the smaller ones.
Several times I have seen M-122s with the badge on the right, and wondered how many of those parts, if any, would interchange with Fs, or if, drool, they were actually Fs in disguise (that is, capacitive). Even if the top half of the case shell would fit an F, that would be nice, because the F cases seem to be a particularly brittle plastic.
