See Figures 1, 2 and 3
The timing mark is on the flywheel and can be viewed through a window in the bellhousing on the transaxle. On some models, there is a plastic cap that can be pulled out. It's easier to see the marks if the cover is removed completely by unscrewing it with an Allen wrench (most are 27mm).
Two marks appear on the flywheel: Top Dead Center (TDC) of cylinder No. 1 is usually indicated with a "0". The only other machined mark on the flywheel is the correct timing mark for that engine. On some flywheels the mark is a machined groove, on others it will appear as a raised lug.