Dickried

What motor do you have in your truck? Because every 5.7 vortec has the same distributor set up and the way you fine tune the timing is by rotating your distributor forward or backward once the rotor is set in place. The 2 ways you can set your rotor are 180°from each other and the reason for that is the oil pump drive gear has an indexing tab on it that has to engage the bottom of your rotor. Anyone who said different doesn't know what they are talking about, and if you don't know that then I strongly urge you to not mess with it and take it to a mechanic.