Just finished restoring the 1970 bronco, so now I have some time to start working on my 68'. Its got a 351w out of a 74 galaxy, and I think its a c4 automatic. (lol definitely an auto, just don't know what kind). After getting a new starter out of an 82' f150 since mine was shot, I started it up for the first time in probably 6 years. The sound that followed from the starter/flexplate/torque converter, was absolutely awful. I've made a youtube video showing exactly what it sounds like and hopefully somebody knows what the hell is going on with this thing, because I'm at a complete loss. I know its not the starter not disengaging, because I bridged the ignition wire to the other side of the solenoid so it stayed on after the motor was started, and it was a totally different noise. The other noise didn't go away when I did this, it was just a compound noise of grinding from different parts of the truck.
Here is the link for the video: