I know that my harmonic balancer is installed correctly, so every other rotation, 0 lined up with the marker on the timing chain cover is TDC.
Instead of a TDC gauge, I use a compression gauge. I put the gauge in the #1 spark plug hole. To find TDC, I turn the engine over, watching the gauge, and the harmonic balancer. On the exhaust stroke, the gauge will stay at zero when the 0 comes around on the balancer. On the compression stroke, pressure will rise on the gauge as the 0 comes around. When the pressure is up and the harmonic balancer is at 0, that's TDC.
Unlike a TDC gauge, you can also use a compression gauge to check your compression.
Cheers,
Duane