1979 L 82 Light Beige with Light beige interior (leather).  This is how it came from the factory.  However, my trim tag says:

According to the BLACK BOOK, the color options AND the leather and cloth in beige were available in 1979. 59 lt beige had 2,951 painted. Lt beige cloth had 8,818 and lt beige leather had 9,181. Base cars were all available in leather or cloth. All quantities are understated by about 7% because of production longer run. Hope this helps.

Thanks, but mostly interested in the tag not matching.  I have the build stats, but thanks for replying.  I can't find the paint code 59L and I am 100% positive it came as leather interior, so the 59C trim code is incorrect.  Just wondering if i may be missing something. I mentioned the codes not being "available" or "recommended" by Chevrolet to highlight the unique situation to start with...that being that it was a "special order".

59L is for 'Frost Beige" paint. The "L" has been discussed as being either for lacquer paint, or, more likely for the distinction of upper/lower body colors on the two toned cars. When the cars were a solid color, the trim tags would read the code with an "L", for lower color. On the two toned cars, the trim tag would have a "u" for the upper color code, and either an "M", or an "L" for the lower paint code.This started with either the '73 or '74 model year.

Code 59C is for Light Doeskin, cloth seats....which is what the car was originally built with, regardless of what it has in it now. The seat material could have been changed anytime after the car was assembled.

Thanks for the heads up on the paint code.  I appreciate the info.  As for cloth seats, the car was custom ordered, original owner said he ordered leather and car was delivered with leather.  I am looking for build sheets in his mounds of paperwork, he swears the car has never had cloth seats.  I will research his stuff more closely.

Not saying it wasn't ordered like that, but that it was originally assembled with cloth seats. If the dealer that ordered it had enough pull with GM, they could have had the seats swapped out at the assy plant, but it's more likely the dealer did the swap. It's also possible the trim tag was mis-stamped....not likely, but possible. On the '79 cars, the trim tag was attached to the body BEFORE paint, so once the body got to the interior install line, the workers would see the tag, and the build sheet, and install whatever interior was called out for.
It would make a great story to find out exactly what took place on the car...it is intriguing.

I thought two tone started w/ the '78 models w/ the Pace car and the Silver anniversary.

On Corvette, yes, but the trim codes "U" & "L" were used on other GM cars too....

How did the trim codes denote two tone prior to that?

There were none for Corvettes before that(if you exclude the cove colors on the solid axle cars), but GM was getting ready for it, plus they were consolidating data for the computer age(ie: punch cards!)