If some of you wonder about the 8 speed cassettes on this bike, I got an explanation; the crafty first owner made a home made 8 speed setup with a Dura Ace hub, mix of XT and Dura Ace cassettes, new Ti axle some distance washer and the friction mode on the XT thumbies. It is all described in an Article in a Montain bike Action mag from -90. The magazine was included in the box. I think he must have bought the Tioga Ti cassette later. 8-speed for MTB came first in 93/94 on the first gen XTR, correct me if I' wrong.
I think I need to find a NOS 7-speed XT cassette to be able to enjoy the full potential of the thumbies.