Install New But Keep Old Radio Clock

I have a 92 Sunbird. I am installing a new radio into the spot below, however I would still like to have the clock show on the old square one, i found out that the head unit of the old one is just a display and the actual radio/amp is seperate. To this there are several connections going to it, and many wires. I would like to know which wires I should splice into the old radio so I can still get it to show the time and am able to adjust it? Below is a picture of what I THINK is the way, the blue dashes represent what should remain on the harness to continue to function the clock...is ther eanything else I need...what do the question marks represent? I beleive i will keep the wire harness going from the left side of the amp plugged in as this appears to be leading to the head unit/face of the radio.

I have actually done this before more than a few times. What you want to do is plug everything back in like it was. Take a DMM and measure the wires going in the display. Find your ground, constant power, and accessory with the DMM and write down the colors on a piece of paper. Now wire your aftermarket radio up and the wires you just found. Thats it.