How one would determine polarity of Altec 808-8G ?

Use a 9 volt battery -- the kind you'd find in a garage-door opener. Touch the battery terminals (or use short lead wires, if necessary) to the spkr terminals. When the Plus battery terminal meets the Plus spkr terminal, the speaker cone will move FORWARD. In reverse polarity, it will move backward.

WARNING!!!DON'T DO THIS!!!!!(What was recommended by Joe A.) I'm sure he meant well, but isn't familiar with the Altecs. I have put low voltages through an Altec 802-8g, on the order of .5 volt and used a magnifier to observe displacement, and the terminal markings are correct - the red is indeed positive. Looking from the back of the driver this would be the left bottom push terminal. Hooked up accordingly, this would give the dome a positive displacement down the throat of the driver, out into the horn.

I was told to use a 1.5V battery, NOT a 9V battery for testing a speaker's "polarity" (phase).