what is the timing on the 1990 isuzu trooper v6 2.8 liter engine with a/c

thank you very much Superbob. i spoke to a local isuzu mechanic here in orlando florida over the phone and he told me that it was 6 degrees TDC. why could there be two conflicting information about my timing marks on this vehicle? also, 5 years ago a friend who had a timing light checked it for me before and i do not remember him placing an electronic spark timing device while he checked it except for the inductive pick up attached to cylinder/spark plug 1. he did attach an engine analyzer (analog) to it to check the RPM levels at the specified timing. Can you please clarify and explaing the difference in procedures? thank you.