Hello to all i have a c3 with all different parts. I want to reupholster the seats but dont know what year they are. I have the seat track numbers and they are 3499. Any help to identify the seat year would be greatly appreciated. T hanks to all 

My initial thought is that is a part number from an aftermarket / used parts company.  I few years ago I looked for a track for an '80 at Carlisle for a friend.  I did a lot of research prior to the trip, and had to use drawings and photos from aftermarket company catalogs and web sites to get the correct part.  The side profile figures were the best ones for me.  I've never seen part numbers stamped in the tracks.  I still have the track I bought a Carlisle as she didn't need it after all as we were able to repair hers.  It is a clean track labeled 78-82, and I just looked at it and it does not have any numbers stamped anywhere. 

Best of luck with your puzzle.  Remember, this is fun!

Thanks 

probably not any help here, but this is from my 72 Coupe built Sept 1971.

243 1  numbers on my seat tracks. What a mess they were to clean up, lube, and repaint.

Good data point Bruce.  I didn't photograph my 72's when I cleaned them up years ago.  Used lots of Brakekleen and even toothpicks to remove the old grease, but all worked out well since they were not bent.  

I dug out my 72 Assembly Manual - it identifies both seat adjusters as 3996859-0.  I'm guessing they are actually 3996859 & 3996860 since they are different with one of them having the release handle.

Perhaps, based on your photos and the 78-82 track I have, the stamped part numbers were dropped at some time.

Thanks for your help

I believe that these may be production date codes, utilising the Julian calendar.

That would be the 349th day of either 1969 or 1979, in both cases, December 15th if I'm not mistaken.    I'm guessing you'll know if the seats are '69 or '79 - '79's must be a bit different?😄

That would make perfect sense in my case. 243rd day of 1971 - that is August 31st 1971. 

The Birth Certificate (build sheet) shows 09-09-71 for my 1972 Coupe. I found the sheet when I pulled out the steering column for the first time. 

Fun fact for my vehicle!  😁