I am getting a strange rattle that I cannot figure out. I hear it from the engine area when I let off the gas and coast soemtimes and when I push in the clutch to shift gears. When I shift gears, it stops the second power is reapplied. The frequency also seems to change as the engine slows so it is something vibrating in relation to the engine, but I can't figure it out. I see no lose brackets or other parts.

Loose engine tin?

broken trans or engine mounts are suspect.

The H/E's tin will rust and the welds will give way. than it just sits and vibrates. (((((RATTLES)))))

Check it out with a rubber mallet or another appropriate tool.

Let us know what you find.

If it's coming from the nose of the engine the cam rivits or bolts are coming undone.

Check everything else first but....

BTW if you do suspect this you can tell by removing the oil pump and rocking the crank back and forth while you watch the rivets.

I agree with Travis. This should be on your list to check. Your noise is torque related. When power is applied it stops or starts? Jack the car then jack the engine and see if it lifts off of its mounts.

It appears that it is likely the outer tins on the heat exchangers. They are both loose. The right one is loose on both ends, the left one only on the back end. When I mave them I don't get the exact, but a similar sound. I will have a local shop reweld them and then see what happens. I will check the mounts when Iget a chance, but they seemed okay when I looked at them 2 days ago.