All trans am cars will have a letter of the vin number indicating it's a trans am. The place in the vin number sequence depends on the year.
For 67-71 2nd digit of vin will be V
72-80 2nd digit of vin will be V, W, or X
81-83 5th digit of vin is V, W, or X
84-87 5th digit of vin is W, or X
88-02 5th digit of vin is W
If car's vin doesn't have the correct letter, it didn't leave factory as a trans am.