These are only my opinions and are based on my personal observations and may not agree with MCA judging guidelines. Having said that, I believe there were three variants of trunk mats that were used in 1968 Mustangs. I am referring to assembly line trunk mats, not dealer added or installed trunk mats (usually the rubber plaid type). The most prevalent trunk mats (based on my observations) used in San Jose Mustangs was the speckled, burtex mat or a gray, burtex-like mat. In the original cars that I have seen or owned, I'd say it's about a 50%/50% split. I have never seen a plaid, burtex mat in a San Jose Mustang. I'm not saying that they never used them, I'm just saying I've never seen one. The plaid, burtex mat was frequently used in 1967 Mustangs (don't know which plants or if it was all plants). The plaid, burtex mat was used in very early 1968 Mustangs as a carryover from 1967 probably. I have a plaid, burtex mat out of a very early 1968 Shelby GT500 convertible with the stitched corners. I'll try to get a picture of it tomorrow. To see a plaid, burtex mat in a GT/CS would seem unusual to me given their late introduction. The coupe mats, and convertible mats, and fastback mats were all cut different from the factory. The reproductions are all cut the same (I think).
Scott