Lode51, I'm in the middle of doing this my self...I had to really clean the fly wheel...crawled under and used a wire brush. There should be a triangle ...hash marks then a small circle...stamped into the flywheel. I used white paint and highlighted them so I could see them better thru the inspection hole next to the atarter.
I didn't have the UDC or TDC mark other folks had talked about. Good luck.
