Quote Originally Posted by chevyfast View Post
So I have a friend who's got a 5.3 for sale supposedly out of a 2007 truck. I'm not sure were to look on the motor to know this for sure it has 862 heads which all the info I could find was that they came on the 99-00 5.3. It has a fan which I thought 05 ups had electric fans. I pointed this out to him which he pointed out it also has electric tb. So I'm confused can someone please help?!!!!!! Thanks!
The 2007 year had three 5.3L motors offered. The 2007 Classic (still a NBS) had the 5.3L with either the L59 (flexfuel version) or the LM7. The 862/706s are on the 99 and up 4.8/5.3L motors. The only difference about the L59 motor was the injectors. 2005 and up motors had the factory electric fans and electric TB.

The 2007 NNBS 5.3L motors (4 variations) all had AFM--either iron block regular 5.3L (LY5) or the flexfuel version (LMG). The aluminum block 5.3Ls were either LH6 or LC9. The LC9 is the flexfuel version and only offered in 4WD models. All 5.3L NNBS motors either came with the 799 or 243 heads and flat top pistons.

REMEMBER--just because the heads say '243' doesn't mean it has the lighter weight valves and upgraded valvetrain like the 243 heads that were on the Z06 Corvette. Any 799 or 243 head found on a truck had the regular valvetrain.

The ONLY truck that had 799 heads from the factory were the L33 H.O. 5.3L. There were only sold in the 2005-2007 Classic model year (VIN code "B") and came in extended cab 4WD trucks.