Also thanks to Swede70 it can be confirmed that the 1968 AMC Jeffords AMX-R was used as the pace car for the 1968 Trans Am event held at Meadowdale International Raceway in Carpentersville, Illinois on Sunday, July 7, 1968. This is the only Jeffords AMX-R ever built and 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 lettering onthe door can actually be seen in the footage!
Swede70 posted a link to some really cool color footage of the event posted on Youtube:
https://www.youtube.com/watch?v=ltof03Knlm0Additional pictures of the car can be seen in Replies #32 & #33 on page 3 and Reply #49 on page 4 of this thread.