TheShoer,
Your new internally regulated alternator has a DA plug. The terminals are marked #1 and #2. The terminal marked #1 needs to be energized as you start your rig to make the alternator begin to charge.
After your engine starts, this terminal actual begins to produce voltage. If you have wired this circuit in series with the coil in any way, and the circuit isn't broken when you turn the key OFF, the alternator will supply enough voltage to keep the ignition circuit charged and the engine will keep running.
If you have wired #1 to the coil, as is often done, you will need to install a small diode the will prevent voltage from flowing to the ignition and causing this problem. Many alternator swap kits contain a DA plug that has a small diode installed in the line near the plug.
Stuart
