1992 Astro, 4.3 with a Z in the VIN #
While playing with the transmission (tonite's lesson was the value of
having a transmission jack) - I looked up at the front of the engine
and was surprised to see what appears to be two grooves cut in the
whatchamacallit (harmonic balancer?) for timing marks. Are they
indeed both timing marks? If so, which one are you supposed to use
when you time it?