Getting the damper back on is a bit of a challenge, since it needs to be driven on with a big hammer, or pressed. To prevent damaging the thrust flange on the #3 main bearing, remove the sheet metal splash pan under the flywheel and drive a hardwood wedge between the clutch pressure plate and the bell housing to hold the crankshaft forward, then use a wood block and a big hammer to drive the balancer on until it bottoms against the timing gear. Removing the radiator usually gives you more room to swing a hammer without doing any damage. Be sure to change the front seal in the timing cover before replacing the cover. The seal is the same size as one for a small block Chevy V8. If the score mark in the hub isn't deep, just shoeshine it with a length of emery cloth to polish away any rough spots. If there aren't any shiny spots on the inside of the timing cover or on the perimeter of the balancer, I have no idea where the screech might be coming from. Did you remove the front main bearing cap and inspect the bearing? Since the noise goes away with the balancer removed, the bearing isn't likely to have a problem, but with the oil pan and timing cover off, now would be the time to check it out!
Jerry
