Ed,
I've never heard of that model before. As far as I know, none of the major companies (loomis, calstar, seeker, lamiglas, all-star...) have any "GSC" lines. I could be wrong, but I've never seen anything like GSC. The closest I've seen would be Lamiglas, they've got some GLB 1082's (MH, 1MH, 1M). My guess would be it's a discontinued Lamiglas. Then again, it could be some old rod that I'm not familiar with, like an old Sabre or somethin, but I didn't get that impression from your post. So, my guess- Lamiglas.
-Brian