is it a real gt k code?

First - buy a copy of Tony's HIPO book. It'll be the best $30 bucks you'll spend.

Verify all 3 stamped Vin#s on the engine compartment inner fenders match - make sure these 3 match the door tag.

If the car was built in NJ (T factory code) it should have a buck tag - confirm this shows HIPO or HIPERF and has the same VIN number.

The only way to 100% confirm a factory GT is with the buck tag showing PI or PIO for Performance Image Option (GT).

Dearborn and San Jose cars don't have this tag - determining a true "factory" GT is a little harder with these cars or a NJ car without the buck tag. There isn't a 100% fool proof way - you just have to look at all the unique GT items to make sure they are there - then look at the special holes for the fog lamp wiring and the switch - do a search on the archives for this - many people have posted good photos of factory holes.

IMPORTANT - confirm that the car has the correct dual exhaust plates under the back seat and in the rear frame rails - PLUS that it has the correct 9" axle plate - a rebody car will have the wrong plate and usually no dual exhasut plates. Again do a search on the archives for good documentation on this.

And finally the block and trans case can have VIN stamps - but Ford did not always stamp every unit. If the block is stamped it will be on the passenger side of the block - just above the oil pan rail below the ground cable bolt flange - you may have to scrape away years of crud and use carb cleaner to see it. The tranny is stamped somewhere on the bottom of the main case - it varies - check the archives again for this.

I hope this helps.

Oh I forgot to add - post some photos if you can - the guys here will help deteremine if it looks legit.