The first Klingon AMT kit I got in the mid 70s was molded in BLACK with some chrome parts for the torpedo tube, the little pipes for the sides of the neck, etc.
Yep! That's exactly the same one I got - and that was around the same time I got mine. Still have it too, but I did paint it, yes, neutral gray.
Interestingly, during the early 80's, a friend of mine got one and the base unpainted plastic was PINK! I remember him opening up the box after we got it at the local hobby store and we both said WTF?!?
I suspect AMT had exhausted their black and white pigments and started to throw damn near any other color they could find just to finish that run. Another friend got a blue TMP K'T'inga, also during the 80's. AMT must have had real problems keeping normal colors in stock around that time.
Back then, it hadn't occurred to us (from a collector's standpoint), but we later thought (in the 90's) that he should have probably kept it in the box, with the parts still wrapped up and just gotten another one to build. Ol' pinky would probably be worth something now.