Odometer quit

Been away for a while, but have a quick question and hope someone can help...Have a 1996 GT, and the Speedo still works, but the Odometer and Trip Meter have stopped working...Tach works, all other gauges work...any idea what the problem might be?

I put her in the air to make sure I didn't pull something off of the trany, and everything is tight...Drove through my alley a week ago, and ran over some tall grass and weeds in the center...thought that might have been it..but it wasn't...

Any help here would be greatly appreciated! Can't find my Chilton's manual, must still be packed somewhere...