Slightly Embarrassing Question

Just out of curiosity - did you dial indicate the bellhousing or verify the engine and trans is sitting in the car 100% straight? I had a vibe in a friend's car that ended up being the angle created by the front mounts not being settled in evenly so the engine was "clocked" slightly off in the chassis, and the output shaft was not pointed exactly where it should have been. It took 2 years for him to realize it. He had tightened the engine mount brackets tight on the engine when it was on the stand, and while you could get the bolts in the K frame it was not sitting level. He found it by looking at the center link in relation to the oil pan with the car's weight on the wheels on level concrete and tires pointed straight ahead.