The Pro Staff Classic was a very stiff frame with a 22mm straight beam and a color scheme featuring the red-yellow gradient in your photo, introduced in the early 90s as a "player's widebody" (in contrast to the Profile, Thunderstick, etc.). In the following year or two Wilson introduced its S.I. ("Stiffness Index," later rechristened "Swing Index") ratings across its lines and at first seems to have assigned 6.0 to the the PS Classic, again as in the photo you posted. These seem to be rare; I've seen only one in person. The PSC was quickly reassigned 6.1, maybe because Wilson had not yet given up on finding a way to capitalize on the Pro Staff Mid that Sampras, Courier, and Edberg still refused to give up, and the PSC wasn't converting enough the Mid users.
Leather grip? If yes, and based on your photo on post 11, seems like you got the PS 6.0 95 that was released in the early 90s just before the Pro Staff Classic 6.1 95. See this TW write-up, scroll down for the 95 review. The PS 6.0 95 and PSC 6.1 95 are different Pro Staff lineages and hence are different rackets with slightly different specs. PS 6.0 95 is a rec-player friendly variant of the 6.0 lineage (PS85, PS90, RF97), so it was a mid plus with a much lower swingweight and slightly thicker beam (19mm vs 17mm). On the other hand, PSC 6.1 95 marked the beginning of a new mid plus Pro Staff lineage that was for advanced players, so it had the same high sw in the PS85/PS90 but in a larger headsize and slightly thicker beam. Henceforth, for each Pro Staff layup variant (Hypercarbon, ncode, kfactor, BLX etc) there would be always be a 6.1 90 (6.0 lineage but for some reason Wilson decided to brand it a 6.1 as well which is one reason why there’s all this confusion) and a 6.1 95 both of which are advanced player frames, and occasionally they would also release a 6.0 95 rec friendly variant (Hypercarbon, BLX). Then when the PS90 was discontinued and the 6.0 lineage was rebranded as the RF97, the 6.1 95 was also discontinued (presumably to focus all advanced player sales to one player’s frame). Years later the 6.1 95 was brought back under the Wilson Pro Labs range and is now back on the consumer market.
The PS 6.0 95 should be referenced in version 2 in the Wilson Pro Staff history you referenced, under “Pro Staff 6.0si”. But you can ignore the info in the caption as it describes the 4.5si and 5.5si pro staffs, not the 6.0.
Right, then both are PSC 6.1 95 with your first racket having the 6.0 sticker misprint. As for the difference in static weight, it might be a case of Asian vs non-Asian variants. I know later Pro Staffs when they started printing specs on the throat had 320g unstrung variant for the Asian market while the original was 340g unstrung.
I don't remember, but I just searched for a photo to count the strings and found only 16x18. It was a niche racket at the time—really just for the old holdouts who refused to use a widebody—so I'd be very surprised if they made more than one string pattern the way they (eventually) did for the 6.1.
