Since there was a bit of 'seat belt date' discussion in this thread, and I'd never checked mine (beyond noting they were 69's), I thought I'd check in more detail. I first went and photographed about half the seat belt tags (the half that were easiest to access). Of the 7 I photographed, 3 were dated '36-A-69' and 4 were dated '37-A-69'. Checking the 1969 calendar, week 36 began Sept 1, and week 37 began Sept 8. My car was completed/shipped on 18 September, so in my cars' case, the belts were 1-2 weeks ahead of the car. My seatbelts are 'standard buckle', and reflected that with the '-A-' mfg designation, and were also labeled with 'IRVIN'. I also did note that the 2904 models had the 37 week dates, and 2950s had the 36 wk date. Since I didn't check all the belts, this may only be consistent with the ones I checked, but the CRG report on seatbelts (by KurtS) stated that this might be the case. (1 paragraph from that report follows)
"The date coding used the following format: A one- or two-digit number indicating the production week, a single letter to indicate which supplier plant (or possibly production line) produced the part, and a two-digit calendar year number. 50-A-68 decodes as manufactured the 50th week of 1968, by Irvin Industries. The belts of the same model number in a car are often dated the same, e.g. the front lap belts (model 2904) in a 69 are likely to have the same date. All standard belts had the letter A for the plant code (except for a few 68 LOS cars which had E & F coded standard belts, perhaps due to a supply issue) and deluxe Camaro belts had the letters C, E, & F."
Thanks to Kurt for a very well written/detailed report.