I have low voltage at startup (ignition on). The car is fine when it is running, between 13-15 volts depending on the loads (electric fan is the main load, no stereo, electric fuel pump, a/c, etc).

Car runs fine, I turn it off, it shows about 14.5 volts, but when I turn the key off, then go to start it up, the voltage drops down between 10-11. This is NOT while trying to crank the engine. I turn the key to "on", and voltage reads between 10-11. I am sure of the accuracy because I have a autometer voltage meter, not the standard amp meter that originally came with the car.

Fan is NOT running while I've noticed this.

70 Cuda
440, mild build
electric fan, no other high draw electronics
lightweight super starter,
electronic ignition with MSD Blaster 2 coil
Powermaster 80 amp alternator

Your thoughts?

and as 440sixpack would say "stab the VOM probes directly into the batt posts"

Could be something as simple as dirty cables.