This is a rebuilt 401 with a matching rebuilt SP300 tranny. With the handbrake on and standing on the brakes, there is a loud noise when I torque it up to about 1,000 rpms in drive. The noise is a loud metal to metal rotating sound. It does not make the noise in reverse. When driving, it will make the noise only when I get on it. It is not a muffled noise like you hear in a torque convertor or transmission which are full of oil. It seems to be coming from the back end of the engine and sounds internal. I have eliminated the following: Flex plate, starter, and anything up under the tranny dust cover. With the car on a lift and using a stethoscope, it is loudest toward the back end of the engine. I know sounds can travel but it doesn't sound like the tranny or the torque convertor. Any suggestions on how I should proceed from here? This is driving me nuts.