I may have answered my own question on which AMX actually paced the race. When I posted the picture of the red AMX at the front of the grid in another thread I created for the Meadowdale Trans Am, CRG member MO pointed out that the car had a rumble seat. I hadn't noticed this before so I decided to do some research and found out that the car is a 1968 Jeffords AMX-R and is the only one ever built. More info on the car can be found in this article: http://www.hemmings.com/mus/stories/2009/11/01/hmn_feature7.html
The article states that, "Jeffords convinced AMC to provide him with a pre-production Caravelle Blue 1968 AMX--its 390-cu.in. V-8 carries a December 1967 build date--sometime in December 1967 or January 1968. Jeffords then swiftly shuffled that AMX over to Dave Puhl, the customizer whose name graced Puhl's House of Kustoms in Palatine, Illinois." This shop would have been less than 15 miles away from the racetrack! The article also states that, "After Puhl finished it, Jeffords took the AMX-R on the road, mostly to Trans-Am races, and apparently used it as a pace car for a few of those races--at one point, the AMX-R carried the lettering "Official Car" just below the driver's and passenger's windows." The use of the word "apparently" seems to mean that their is some doubt if the AMX-R actually paced a Trans Am race, so maybe this picture just might be the evidence needed to say that it did? Does anyone have a picture of the actual pace lap?
In the second attached picture you can see the AMX-R behind the Trans Am Javelin. This picture is from: http://miroldpix2.homestead.com/68transampage.html
The third picture is how the car looks today fully restored (internet picture).