Is this a Specialized Stumpjumper, or not?

[ish]

It's not a Stumpjumper. Stumpjumpers were still steel in 1992. This bike marked a major new direction from Specialized. In later years there were indeed M2 Stumpjumpers, but the bike in your picture was the team issue machine, near identical to what was being raced by Ned Overend and others at the time. In later years these frames had the S-Works designation on the downtube instead of the double Specialized decalling.

This is not entirely correct. The 1991 Stumpjumper M2 and Stumpjumper M2 Team were branded as Stumpjumpers.

I perceive this bike as a Stumpjumper, but perhaps that's just me.

 

[stumpjumper1990]

It's not a Stumpjumper. Stumpjumpers were still steel in 1992. This bike marked a major new direction from Specialized. In later years there were indeed M2 Stumpjumpers, but the bike in your picture was the team issue machine, near identical to what was being raced by Ned Overend and others at the time. In later years these frames had the S-Works designation on the downtube instead of the double Specialized decalling.

This is not entirely correct. The 1991 Stumpjumper M2 and Stumpjumper M2 Team were branded as Stumpjumpers.

I perceive this bike as a Stumpjumper, but perhaps that's just me.

You are right! There were M2 Stumpjumpers from 1991. Take a look at the 1991 catalog.

This bike was called the S-Works M2 Team as you can see from the scans of the 1992 S-Works catalog on the first page. I'm not sure, but it is possible they had different names in different countries. Don't think so, but it is possible....

 

[ish]

Someone should correct the 25 Years book and the ad for the 1992 Team bike, as they both mention the Stumpjumper M2.