I went to the address and spoke to the current owner. I had perfect timing showing up as they were both out on their front yard.
The new owner said that he had just moved there about a month ago. He said he knows the last name of the previous owners that lived there before he moved in. But it wasn't Gregory's last name. He said that those previous owners had been there at least 3, maybe 4 years. So that means Gregory who lived there before them, must've sold the car approximately 3-4 years ago when he was at that residence. Sounds to me like he was cashing out and had new plans. Maybe that Texas lead could be legit?
I left the new owner my cell phone number and asked him if he would kindly do the favor for me by contacting the realtor to see if they could trace Gregory. I told him it would be important for you because he would like to get the build sheet on the Challenger you now own. (Whether thats true or not it sounded good)
If and when I get any update; I'll be sure to let you know willard.