My Strato Buckets have a different kind of material, hard to describe, but more of a silky Fabric and not
What constitutes a "Strato" Bucket Seat? The type of material or the fact that is simply a Bucket seat? How many of you have Vinyl and how many have the "Fabric"?
As far as I know, GM introduced the "Strato Bucket" seats for the 1966 model year and they were used in many models. "Strato Bucket" is what GM called this specific bucket seat design
; the name is not dependent on a particular model's interior material or stitching pattern.
I believe that Strato Buckets were used in all GM A-Body intermediate cars from '66-'72 whenever bucket seats were specified, and therefore they are what our bucket seat-optioned Monte Carlos have in them from the factory - regardless of cover material or pattern. As seen in the photos already posted in this thread, Strato Buckets have a fairly thin vertical seat back cushion that is backed with a hard shell. The "shell" continues around the seat base as trim to tie the design of the seat back and seat base together. I believe that head restraints were optional on Strato Buckets from '66-'68 and were standard from '69-'72. In first-gen Monte Carlos they were available with all-vinyl or cloth/vinyl covers.
If you compare '65 and '66 Chevelles with factory bucket seats ('66 would have the Strato Buckets), you will notice the differences between the earlier bucket seat design and the Strato Buckets. The earlier design was chunkier-looking, and considering that the vertical seat back of the Strato Buckets is thinner (when viewed from the side), I believe that they aided with rear seat occupant leg/knee room.
My '70 SS454 has its original code 749 interior in it - Black Cloth Bucket Seats. And yes, these are "Strato Buckets". The "cloth" on black seats (at least in '70) is a nylon-type, and like you described, kind of silky. I believe Chevrolet referred to it as "knitcloth", and I've also seen it called "Prima Cloth". I'm not sure if it's the same material as what's in your '72 or not, but it sounds like it could be. The "knitcloth" is on the seating surfaces only, with the sides being vinyl. It's a great, long-wearing material and it's not as hot as vinyl in the summer.
Hope this helps.