OK, Gary Fisher, IIRC, are made by Trek.
Bontrager is their wheels-and-forks-and-such company. Shimano makes shifters, cogs, chains, etc: Drivetrain stuff. Rock Shock (sp?) does a lot of bicycle suspension parts.
There should be a serial number on the bottom of the frame, under the crank area (the bottom bracket). It might also have model information, which can be Googled pretty easily, I imagine. If nothing else, call up Fisher/Trek CS and tell them you bought a used GF bike, but it's been heavily modified, and ask them what model it was at the factory. The serial # should be useful there.
Also, see if you can find other markings, names, etc. on the component set.
(former bike geek here)