SK 7/2: Armor Efficient? (FoF)

[Poor Yorek]

In FoF, the SK 7/2 are defined as SPA (citing 5.64) even though they have no printed armor value (treated as a truck with armor = -1).

The question, though, is whether its 2-5 AT value is efficient as an AFV? AFV's, of course, are defined as "any unit with a printed armor value, even one of zero." On the face of it, then, these are not AFVs and, therefore would not qualify for armor efficiency (in comparison with such as the Wespe with its 5-6 AT value and '1' armor).

Yet, these are light AT weapons mounted in an mechanized "half-track" - technically the SK7 prime mover. Is this so different from SPW 251's mounting AT capable weapons which are AFV's? I suppose one could return by arguing that the latter weapons were designed "into" the half-track, not simply "carried in the back" and, of course, the SPW 251 was "armored." Note, however from Wikipedia: "The Sd.Kfz. 7/2 was armed with a single 3.7 cm FlaK 36 anti-aircraft gun. On many of these variants, the driver's position and the engine cover was armored[1]"

In any case, just wondering whether anyone else has adjudicated this and whether there were any consensus. The literal rules would seem to suggest "NO" to armor efficiency, but just curious if this was a case of something slipping between the rules.