I ran into the same thing, one of the holes is slightly off from the others so you can only put the flywheel on the right way.

Quote
Originally posted by atomarc:
I think technically that the ball-on-pointer location is really several degrees before TDC, as this is a timing mark and not the actual mechanical top of the stroke for #1 piston.
Yep, thats it. At idle the timing is set so that the ball is on the marker. Should about 5 degrees before TDC, there is a line on the flywheel near the ball that is the actual TDC marker.

1956 GMC 370 dump " 'Tater "
1970 VW Volksrod "the Black Bomber"
2007 Chevy Avalanche
2020 Jeep Cherokee Trailhawk,
2005 Harley Davidson FLHTCUI

I dig all cars, old and new, whether they were hammered out of American iron, German steel, or Japanese tin cans. Being unable to appreciate them all is missing out on a world of great things.
But thats just MY opinion! :P