Depending on year model and interior color - pretty sure the 454SS seats are unique to the 454SS and were not used in any other GMT400 model. They're a highback bucket but not the *exact* same style as what you posted.
The first picture with the dual armrests are Suburban (and possibly Blazer/Tahoe/etc.) buckets seats; the second pic with the single inside armrest are regular pickup buckets.
Original 454SS buckets are red, with the "stripey" Silverado style material, have no armrests, but have side bolsters.
Pic from a 1990 model:
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Now it does seem that the later years where you could get different color interiors, they used the regular highback buckets with the inside armrest and no side bolsters. I don't know if the later models with red interior went to the regular style seats. Lots less pictures of 454SS's after the 1990 model because production #'s dropped significantly, and there were hardly any 1992-1993 models made by comparison.
Many of these trucks have been stolen/stripped/rebuilt by now and I've seen quite a few with very obvious non-original interiors, including some with the very early LOW back buckets from a regular 1990 Silverado. No headrest, no armrest, and very "square" looking seats. These are not 454SS equipment; the owner put them in his '93 for the tiny little bit more legroom they allow.
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I'd say unless you got really lucky and scored the "real" ones with the side bolsters.. I'd go with the inside armrest highbacks and call it good. They're comfortable, good looking seats.
Richard
