If the starter is not releasing, I can't agree with "the solenoid works fine".

Is this a new problem that only began after rewiring for the new distributor?

Have you tried Dave's suggestion in post #13? Pull the wire from the small S terminal on the starter relay (aka solenoid). If that doesn't release the starter, the starter relay has failed in the on position. If pulling the S wire releases the starter, there's something wrong in the control circuit.

If the starter relay has failed, is it new? LOTS of trouble with replacement relays, with plenty more details here:

https://www.ford-trucks.com/forums/1...i-mean-it.html

 

As best I can tell now it's not the starter. I just started it again. The noise is coming from the back of the engine, near the bellhousing. I can feel it vibrating in the shifter. Trans engages and truck will move. The noise doesn't increase or decrease with engine speed, in fact it seems to lessen with higher RPMS. I just had a new clutch assembly (including pressure plate) installed just a couple of weeks ago. They did change the fluid in the trans. Didn't have this noise at all until I swapped the distributor. I think that's a coincidence. I thought maybe the new distributor had a bad bearing or something or the oil pump drive wasn't fully seated but I have oil pressure and the distributor is completely seated in the hole and the clamp is tightened down. Before I changed the distributor I had multiple episodes of VERY bad backfire through the exhaust and the truck would just die randomly. Would start right up again immediately but every time I stopped at a light or an intersection it would quit. Like it was fuel starved, which it wasn't. So I figured the distributor module was going bad and since I was going to swap it anyway I went ahead and did. Could a couple of severe backfires blow out the honey combs in the cat converter and make them rattle? It's not the heat shield, I checked. If the trans failed, What made it suddenly get noisy after sitting for a week. This noise didn't exist a week ago. I want to love this truck...

 

Transmission noises usually change with different gears selected. A severe backfire can ruin the cat as well as the baffles in the muffler.

 

Can you record with your phone and upload it to youtube or something with a description? Will probably help a lot with troubleshooting a random "grinding" noise since we all probably define that differently.

 

I'll do that this morning

 

Everyone...
THANK YOU all for your advice and offers of help. The grinding noise turned out to be the starter drive not disengaging all the way. It would pop back about halfway, just enough for the first 1/8 inch of the gear to grind on the flywheel. New starter...no noise. The HEI Lightning Whirler is OUTSTANDING. The truck starts so fast it'll scare you and it even SOUNDS better. I do think the distributor was at it's end. In the process of replacing the distributor and wiring it in, I discovered how BAD the wiring harness is in the engine bay. Bare wires galore. Mice, heat,age deterioration have taken a toll. So now I need to find an OEM harness somewhere.
Thanks again everyone.

 

Yeah a bad starter is a serious yikes moment. Glad that got sorted out. I'm probably going to put an HEI one in my 82 when the original finally gives it up.