Hello all, my '07 Avalanche has 215K miles on it. It has the 5.3L and I locked out the AFM with a device I plug into the OBD reader spot. It blows white smoke on start up, has an oil pan leak, a rear main seal leak, and one bad hydraulic motor mount. Since I will have to remove the engine anyway to fix the leaks I thought I would put a newer and more reliable engine and transmission in it. From what I've read, the 6.0L is the easiest swap. What model engine would any of you suggest and what transmission would be best for towing? The body and interior are top notch and I don't want to pay $50k+ for a newer truck. Any suggestions would be appreciated.

 

If you are switching up transmissions and engines, you will need new engine and transmission control modules, as well as a new wiring harness to match. And reprogramming by someone with the equipment that makes it all match your VIN, for everything in the vehicle to work together properly.

MAYBE the 6.0 can use the same harness as the 5.3, but regardless, the ECM would require reprogramming or replacement - otherwise it thinks it is controlling a 5.3 versus a 6.0.