My bet is it's a broken drivers side motor mount allowing the motor to tip up under hard acceleration and that allows the fan to hit the shroud making a grinding noise. Had that happen quite a few times personally and saw it many other times on cars I worked on when I was young.
If the K frame is the original for the car in your title it is a biscuit type and they are the ones that commonly break. They are a slab of rectangular rubber with studs sticking out both sides. Spool mounts are round and have the retaining bolt going in from the front with a nut on the back.
A real quick easy test to see if it's a motor mount is to open the hood and have a buddy stand beside the vehicle (wearing eye protection just in case) and they you set the parking brake and put the car in drive and hold the brake real tight and give it some gas. If the motor comes up more than 1/2" the mount is broken or oil soaked so bad it is like a sponge.
