I believe you will find (if enough research were done) that variations exist by suppliers and dates. Keep also in mind that a Tilt column connector color COULD be different at the same assembly location & date.
Wire loom and the related details are interesting IMHO since there was a number of suppliers and some of those subcontracted out to even smaller companies or even individuals to build so of them. Believe I've shared this before but in the late 60's early 70's while on vacation and traveling across the Calif/Nev desert we stoped to get gas and in the work space the employee (may have been the owner) was assembling electrical wire looms for Lincoln power seats.
With that yes have seen many discolored but many that were not. It's not like the location really got hot or any sun exposure so not as likely to discolor IMHO when compared to those located in other areas of the car but I think we all accept that plastic can discolor some just from age.
Found it difficult to find many pictures since these are, on an assembled cars), up and often out of view so good to have some pictures of disassembled cars from projects or yards.
Top two San Jose cars in low teens. Two lower Dearborn examples - left from a tilt
From the late 67 San Jose 390 fastback thread in the Unrestored Picture thread. Unfortunately very "bleached out" from the flash I was using
Lot of "rose" colored ones
All 67 San Jose examples.Some appear to be rose while bottom two are discolored. Uneven finishes
And a very nice very low mileage NJ built Mustang provided this picture
Hope this helps
