Answered my own question: according to Bikepedia, it's cromo seat tube; hi-ten everything else, i.e. the same as the GX7 in the catalogue as, I suppose, the paint job suggests. A post-catalogue name-change perhaps.
The GSX isn't in that catalogue and I haven't found one with the details you are asking about.
What I can say is the the words direct drive are in several places on the frame and forks. It says "Direct Drive Custom" on the seat tube and Off-Road Cromo and then something beginning with SF but the rest of the lettering has worn off on this particular example.
On the forks the two capital D's of the Direct Drive are above each other and touching to look like a letter B. I wondered if it was designed to say or imply DB for double butted but....