I've had a pulsating engine vibration regardless of whether the car is moving or standing still and I've reved it up. Just for grins I removed the (fairly new, but too old to return) steel fan and thermal fan clutch and ran the engine standing still - presto, no vibration. I put on the old aluminum flex fan and still no descernable vibration. Clearly the relatively heavy steel fan or clutch unit was the cause. Has anyone heard of this? Seems a bit odd given that this was the OEM setup on the '69. It's hard to believe that one of these two components is that far out of balance. For now, I'll just roll with the flex fan, but I wondered if this was a semi-common problem or others had encountered it. The fan mount on the front of the water pump has a nose that forces the pulley and fan clutch to center when mounted, so they aren't mounted off-center.