Someone on here was looking for or trying to find out about "Frame ID." Just wanted them to know that the "Frame ID" on the C3 is on the reardriver side of the side frame memberjust forward of the back corner and/or on the back cross member just off centerto the driver side.I found this in my '81 'Vette GM manual. It doesn't explain how the date is stated ie; in numbers, letters, combo of both, etc.
Sorry for the late info. I stumbled upon it by accident.