i agree with djr81....however with mine, I was told that engine was rebuilt, gearbox rebuilt, and had a new clutch. As it turns out, clutch was reco'd, engine wasnt rebuilt but more patched up...which made the problem worse, and so far so good with the gearbox. If they say its been fixed, its not such a bad idea to check where and when it got fixed, then you could simply call the place up and enquire about it. This however is not really neccessary. Its just an extra precaution. You dont need to pull the head off to check what the deal is within the block. Compression and leak down tests are the best ways of finding out if the motor has any issues. Like djr81 said, its better to take the car to a place that knows GTRs than just your average mechanic.