Leftover letters on patched-up sign for Interstate 980 in Oakland

The sign for "Downtown Oakland" in this gantry for eastbound Interstate 580 traffic in Oakland has gone through changes over the years. Signs of an earlier designation, probably for California 17 (later Interstate 880) appear with the letters "S" and "H" that are now covered up by the Interstate 980 shield. There's also greenout on the Interstate 580 through-traffic sign. That's probably covering up a US 50 marker that would have been originally on the sign. Both signs were the old-style button-reflector signs when this photo was taken in July 2008.