Which mark is top dead center on harmonic balancer

SOURCE: where are the timing marks on a 2000 gmc jimmy to

look in front of motor, down to where harmonic balancer is on the front of motor, should be a timing tab on timing chain cover, pull no1 plug out, hold finger on the spark plug hole or put a rag in the hole just enough to get it to blow out, bump motor over a little at a time when the no 1 piston comes up on compression stoke, it will blow rag out of hole, or it will blow out around your finger, you might have to put wrench on balancer to turn motor a little,stick screw driver in hole to see if piston is high as it will go, pull distributator cap, see if rotor button is pointing to number one plug wire on the cap, also check balancer to see if any marks are showing, somewhere on the tab on timing chain cover, if so should be in time or close, you may have to put timing light on it