[Woodie83]

Is the grinding sound constant or just when you shift gears? If constant, might be a wheel bearing. If just when you shift, check the clutch adjustment for freeplay. Your pedal should move half an inch or less by hand before you feel the resistance of the clutch. If you stand in front of the driver's seat and look straight down between the distributor and the battery you will see a six inch long lever with a cable connected to it on the battery end. The other end goes into the bellhousing and works the clutch. There's a screw adjustment on the end of the cable. Tighten that up until there's no slack in the cable, then back it off one full turn, maybe one millimeter of slack. Also could be low or wrong transmission fluid, these cars require pretty thin fluid, mechanics often put in standard fluid that's good for most cars. It works in the summer, but when the temperature gets below 30 it gets hard to shift. Needs 75W-90 GM Synchromesh.