This is a long shot. I had a similar noise (grinding) in a 2000 S-10 Blazer. It was most noticeable during acceleration. It got worse after the intake manifold gasket was replaced.
Looking under the dash the noise was coming from the accel pedal cable. I trace the cable under the hood and found one of the tie down point for the cable was broken. I fixed it with a tie wrap, the noise is still present during acceleration but is much more subdued. Since I know the noise is not due to a mechanical problem I don’t worry about it.
Ed B.