Had the same issue recently.
Process of elimination is the only way to track it. Mine turned out to be the alternator, which is still in good working order and the shaft has no movement but was the issue none the less.

Can you post a short video of the car when its making the noise?

I'm going to call Jody Haag from Jody's Transmissions when I get a chance. He sold me the Mcleod clutch kit and may have some suggestions. Another thing I thought of was that I used a GM roller pilot bearing in one of the two 454's I built in the last few years. Unfortunately I don't recall if it was mine or dad's engine. Some internet chatter says the roller pilot bearings aren't up to high rpm use and were to be used for diesel applications. I'll see what Jody has to say.

Steve, I'm real tech savvy but I give it a shot next time I'm there.

The roller bearings shouldn't be used with the Muncie transmissions. A bronze bushing is best, but not one of the bushings that has iron mixed with it. If a magnet sticks to it then don't use it. AutoGear makes good bronze bushings, and you can still get them at some auto parts stores. Jody probably has them too.

A 71 Chevelle if it is somewhat stock will have a charcoal canister under the hood on the radiator support. There is a vacuum line that goes to a check valve on the top of the canister. There is a seal this that will dry out and can cause a whistle or squeal. Perhaps this is what you are hearing if you can't otherwise locate it.

Did you check the oil ;)

Old cars - Old tactics. Get a long screw driver Put it against every area/part of the motor and put the other end against your ear. It will be noisy but it should tell you if it's at the front of the motor or back. If you can get the car on a hoist you should notice if it is louder underneath. Try the screw driver every where including the timing chain cover, oil pan and trans pan. Might as well try the axle and posi bearings and trans tail shaft while you are there. Disconnect the speedo. If you get desperate pull the trans. It's not that hard when the car is up in the air. If it turns out to be the throw out bearing or bronze bushing you will be pulling the it anyway. If you still can't find it do it all again with a piece of heater hose. It makes noises more subtle then the screw driver.

Good luck.

PS. Check for a smart ass mouse in the glove box ;)

Ziggy, get with the times. We have a couple of these.

https://www.princessauto.com/en/mech...t/PA0008885576

Works a lot better than the screwdriver-to-the-ear method.

On sale now for $7.49

I spoke with Jody yesterday and he also said a roller pilot bearing is a no-no with a Muncie due to the hardness of the rollers vs. the input shaft. He said because it does it in neutral with the clutch disengaged it should rule out the TOB and pilot bearing. His records show I bought the clutch kit in 2016 so it's been together longer than I thought. I'm on vacation next week so I'll take some time to go over everything again with a stethoscope before pulling the transmission. Maybe get a friend over to help with a video and a fresh perspective as has been been suggested. Thanks again for the help.

What I do not understand is you said the noise did not occur when the water pump belt was removed. Doesn’t that mean the noise is coming from one of those driven parts?

Jason

Yes, but I don't know what else to try at this point at the front of the engine. I'm going to revisit everything when I get a chance.