First let me say I love the pictures. But am I missing something, I frequently do. And please know I'm not trying to find fault, just trying to help. OP is looking for 68 GT500 #703, purchased new in Dallas, Texas. The Registry says #703 was first used as a demonstrator at AL Grillo in Lynn, MA and appears to have spent it's known life in the northeast. Could it have been transfered to the Dallas dealership after its demonstrator service at AL Grillo?
Respectfully
Ted