Scoring a 4.8 or 5.3 with 243 factory heads tomorrow. It's out of a 2007 Tahoe. I've been told that 4.8s didn't come with 243s only the 5.3s? Can anybody verify? I'm only paying $150 for the whole thing so I'm pretty happy. Also, is there a way without the vehicle vin to identify what it is WITHOUT pulling it apart? I know of the pistons but not casting numbers.