[dagnabbitt]

I've heard or read that low back buckets in early square trucks account for, like, 1-2% of total productions numbers, so they are quite rare indeed. I think it might be much less, I have never actually seen a truck (in person) that was "born" with them.

Possibly they are not as rare, though as the truck-style brackets and sliders! Since Blazers also had a nearly identical low back seat (they just had plastic backs on them) - but different brackets due to their flat floor - there are actually more buckets than brackets available for sale in the used parts market. And, as TKCR notes, very few people bothered to grab the additional "A" shaped bracket needed since it needed to be cut or chiseled out.

I personally think it is one of the best looking buckets GM made, I love that little medallion in the centre. So 70's.