1996 rs tranny problems.. please help!

[propagandhi420]

hey, i bought this car a few years ago with 113,000 km...(5 spd) ran just fine for 3 years but the clutch would slip a little somtimes when i drove it real hard.. well i was driving through toronto a few days ago and i heard a noise and then i felt a real bad grinding through my shifter... felt like it was at the bottom of my shifter.. i dont much about cars but all my gears work fine...and it only starts grinding when i let off the gas and the revs are comming down.. so i threw it into neutral and it still grinds!! only time it doesnt grind is when i'm in gear and accelerating.. took it to mazda dealer.. they charged me $50 just to tell me that it needs to be torn out and fixed.but they dont know what it is.. i'm planning on doing a bpt engine swap and protege lx tranny in a couple months.. so i'm not sure i wanna put alota money into a tranny i'm gonna tear out in a month or 2.. if anyone has any idea what it might be...or if i should just give in and start my bpt swap early. i'm dieing for a car right now. like i said, i dont know much about cars, so any help at all would be appreciated.. i've done alota research on the bpt swap.. but any info or swap guides, or lists of parts i'll need to round up would be great.. THANKS!!