Good luck getting many responses here in just a few hours... Maybe a few weeks... Check the usual things as you would on any used car.... Realize that the TH has been run and run hard, many times... But that's okay, it was built for that. So, I'd run it hard on my test drive too. If you can (legally and safely of course ) I'd make a couple of 1/4 mile passes. Your 0-60 times should not be over 3.5sec and the 1/4 in well under 12, even in this summer heat. It should be super stable and no vibration. Pull up the performance pages and see what your oil pressure and trans and water temps are after a few hard runs and normal driving. Should be normal or thereabouts.