I have a 2007 Yukon Xl 4x4 that blew the engine. I ordered a replacement LC9 engine that was removed from a 2008 Chevy Avalanche. The mechanic used parts from my old engine ie manifold,oil pan etc and installed engine however it will not start. Did I get the wrong engine or will this work? Any suggestions would be very helpful as I know very little about what to do at this point. Thanks to anyone that can help.

I think you have the wrong reluctor ring on the crank. 07 was the las year of the 24 tooth ring and in 08 they went to a 54 tooth ring and changed it to a grey crank sensor from a black sensor. To make it work I think your going to need to program the PCM to 08 specs and make sure it has the grey crank sensor.

Thanks Racer. I forwarded on to my mechanic and think he can fix. He knew the sensor was incorrect but now we know how to fix

He is also going to need to wire a new plug to the harness because they are different between the black and grey sensors.

Where were you 2 months ago when I was doing my V8 swap?

I was watching you finish installing your vortech motor! I think you made the right choice going with the vortech over the LS motor. If you went with the LS motor you would have to deal with a whole different harness, coolant lines, AC lines and different mounts.