84 Saab 900- grinding noise when excellerating

This just started occuring in the past few days.
Saab 900 Manual trans.

When I excellerate, I hear, and feel on the gas pedal, a metal grinding sound. It seems to be coming from the right front side of the car, or directly below the shifter. It lasts for a few seconds, and them seems to stop when I am moving along, it starts again when I shift into a new gear, and then stops again when Im speeding along. This cold morning, I drove to the store, no sound. This afternoon, I drove again, and the sound was there. Could it be that I need to change my diferential / transmition fluid?
Thanks for your thoughts.
Cris

I'm not sure about in the 80s, but in the 70s Saabs were notorious for broken engine mounts. The engine torques itself up under load and the fan hits the fan shroud. In the case of my friend's 74 it broke while under full throttle and the valve top of the engine put a nice dent in the hood. :)

Does it sound like popcorn, especially in a turn? Then check your CV joints.