Having experienced a damper pulley launched into the radiator at 60 MPH, I highly recommend this modification, it sounded like a grenade went off under the hood...Fred's method is undoubtedly the right way to do this, but I did it in my driveway on a 228 GMC with an electric drill and a hand tap. I used a grade 8, 1/4 X 28 bolt and a big washer. Torque ...?? a lot ...Also used JB weld on the threads. Not the most elegant of repairs but it was a daily driver and had to be ready the next day. It lasted for another 25K miles or so, at which time the engine was retired. No vibration problems or other ill effects.
