Alpine 7140E Wiring?

I have an older manual for the 7138 and the 7146 but nothing on the 7140E. Like anything else you can guess at the wiring or get a diagram but here are my thoughts (they could be right or they might not be):

If it is from the same era as the 7138 and 7146 I would tend to think the radio is a common ground meaning the ground for the radio and the negatives from the speakers can be grouped together (this is from years ago when radio's only had a few watts of output like maybe 6-8 per channel).

I would also tend to think the red would go to an ignition 12 volts and the yellow to a constant 12 volts. This seemed to be pretty standard though Alpines wiring.

I would maybe think that the blue, green, white, and gray are the 4 speaker positives.

The best way would be with a diagram or by using some god test equipement on a test bench. I've also seen before internally on the radio circuit boards labeling as to what solder pad does what and then you figure out what wire goes to what pad. 

I would also check and see if you can find out if that particular radio had any external noise suppression filters inline on the power wires. I noticed some on the Alpine radio's from years back and if they are missing you may have some noise problems.

The wire for the 8007 I think was for a security system or cell phone interface.

Jim