What is the proper voltage on the factory gauge when the truck is running? The reason I ask is I have been having large fluctuations, form 12-13 volts, up to 15 volts. Also, are these fluctuations normal?

Key-on = 10-12v with Wait-To-Start, 12-13v with indicator off

Running - 14v

Indicated voltage is dependent on gage accuracy and how much loading - headlites on, ac compresser and blower motor full on, windshield wipers on, 3000watt boomer blasting, 12v-115vac convertor running coffee pot and microwave oven, significant other blow-drying hair, etc.

At 70kmi, have the alternator output checked, and do the basic winterizing procedures - batteries, battery cable cleanup, clean and tighen grounds, etc.