hi everyone i was wondering if anyone could give me some advise on this motor.i have a chance to buy a rag car but a very low mile ,well taken care of supposed 455 sd.could someone tell me how i might at a glance tell if it is a true 455 sd.thanks any help would be appreciated.also it is in a 1970 gran prix.is that even possible ,most of the articles i have read mention the trans am ,which i understand is more interesting to most but i have always been a fan of the older gran prix.thanks again  

check the stamping at the front of the block by the water pump..go to the library to ALL DATA and check what the code means.