I think most GT frames are quite random serial number wise.
Best bet is to look at the colour, decals, and any distinguishing features (frame gusset position, cable stops, shape of rear brake spider etc). If you then look at the catalogues in the Gallery section to track down your model.
Otherwise post a photo of it on here and we'll do the legwork for you.
Hi Sorry but I didn't weigh it as I wasn't concerned about the weight, plus it came with the BB removed. When I rebuilt it I used an external modern Hope BB and Race face Evolve Crankset. Sorry I cant help but there is loads of help on the internet about removing your BB etc