power issue

Check your battery cables and terminals and do a voltage drop test to the starter to determine if you're getting full power to it. Test the ignition circuit and ignition module; http://easyautodiagnostics.com/ford/4.9L-5.0L-5.8L/ignition-control-module-tests-1

Thanks for replying ken...ignition module test is only for crank but no start, my truck doesn't even get to the point of crank so I can't test that...it acts like a bad starter issue but that doesn't explain the difference in voltage as far as the volt meter and the dash gauge with key in the 'on' position does it? As far as voltage drop to starter I can check that....I did check power between the battery and starter relay inside the passenger side fender n that seems to be is it possible it's the ignition switch itself?

*seems to be ok

I would look at ignition switch. Also if I'm not mistaken the voltage gauge gets it's reading from the voltage regulator, you'll have to look at a wiring diagram to see which terminals on the regulator feed the gauge, then you can test the voltage at the terminals with a meter and see if your gauge is reading it right.

Thanks for your input...I'll go through those possibilities this weekend