Originally Posted by 05GTO
It looks like a C176 which is March 17, 1966 and was built on the night shift, the casting number is also correct for a 389, on the front of the block you will find a letter code that will tell you if the motor is original to a GTO. Also, the heads should have 093 on the center exhaust ports
The vehicle build date on the data plate may be 03C, 03D, 03E or 04A.
I'll check out the letter code on the front of the block for being original to GTO. By the way, what letter code would indicate GTO?
The heads do have 093 on the center exhaust ports.
Also, here is a picture of the data plate.