Head Unit Installation Trouble

Alright, I have done many head unit installations, but I have never come across this problem. I am doing in install for a friend's gf who drives a 1991 Chrysler New Yorker. I remove the factory radio and begin the process of connecting the wires of the metra harness and the head unit harness. First of all, the head unit harness does not come with a diagram of what wires are what color. Of course they are not labeled either. I manage to wire the head unit fine, I think, except the ground. The factory harness (actually there are two) have no ground wire. ALso, there is no point that I can see or reach that has any sort of part of the chassis exposed to ground to. I am absolutely stumped. If anyone has done an install on this car or has any suggestions about another way I can ground this head unit, I would appreciate it. Can I run a long ground wire somewhere? Any suggestions welcome. Has anyone ever seen a factory harness or metra harness without a ground wire?? The head unit harness has one, but that doesn't much help because I have nowhere to ground it. Thanks

Grounding a head unit with a longer than noraml ground is usually not a problem. In fact a lot of people will run a ground off the chassis of the deck back to wherever the amp(s) is grounded. this is called a source ground and can be really helpful in getting rid of that pesky engine noise when all else fails.

Chrysler products usually have a separate ground clip an the back of the radio, sometimes it is a woven ground strap. If neither of these are present, runa 12 or 14 guage wire to the nearest chassis metal point you can find, scrape away all paint and clear coating/primer, and tap a screw using a lock washer. this should provide adequate grounding for any head unit.

you are probably already done though given the time, but hey I just like to type stuff!