we have a 66 GTO the casting number on the cylinder head shows a 47 on the cylinder heads i run the number and it comes back as a low hp 350 head. as far as i know the car is suppose to be all original has anyone seen this before thnaks tony https://web-cars.com/phorum//read.php?3,43903,43903#msg-43903 Sat, 13 Jun 2026 03:38:16 +0000 Phorum 5.2.23 https://web-cars.com/phorum//read.php?3,43903,43903#msg-43903 https://web-cars.com/phorum//read.php?3,43903,43903#msg-43903 t Pontiac GTO Forum Sat, 05 May 2012 15:01:46 +0000