The regular model is generally referred to as a “Standard”.
Standard and XR-7 were different models, with XR-7 being more a more luxurious model.
Eliminator is an option that was only available on the Standard models. It basically makes the Standard model more sporty.
I believe Trovit is more of an archive of various car listings and many of them can be quite old! I would stay away from there as far as shopping goes.
Here a few to try…
https://www.hemmings.com/classifieds/cars-for-sale/mercury/cougar/
https://www.cars-on-line.com/mercury.html