Cylinder Numbering (front to rear): Driver's Side 4-5-6; Passenger Side 1-2-3.

Base timing: 10 degrees BTDC (non-adjustable).

Firing order: 1-4-2-5-3-6.

Also, keep in mind that the EDIS ignition on the 3.0L vulcan fires the 1 and 5 cylinders at the same time, the 2 and 6 cylinders at the same time, and the 3 and 4 cylinders at the same time. The reason for this is because the 1-5 plugs are in series, as are the 2-6 plugs and the 3-4 plugs, respectively. Here is a nice diagram of that (thanks to Bob Ayers for providing it):