So my buddies got a 2003 Chevy 1500 with the 4.8. He got a bad knock the other day out mudding. He wants to swap to a 6.0 lq4 or lq9 depending on what we can find. If I can find an engine with the harness and all what else would I need? I have hptuners so I could load a stock tune and go from there if it will still work with the same computer? Also didn't the 6.0 come with the 4l80e? Im sure his is only the 60e. We may have to get engine and trans in that case, I know the 60e doesnt last too long with more power. Any info would be great, thanks

 

You shouldn't have to replace the existing harness unless you go late model with the engine. I would just get a long block out of a 06-earlier(and trans if you wish) and tune it. You might want to grab the injectors from the 6.0 but even those might be the same. 4.8-5.3-6.0 have very few differences and generally no external differences. Swapping the harness and PCM would be required of you go to something with a 58x reluctor wheel. Google will tell you the exact years.

 

Thanks for the info. Would anyone happen to know how much different the transmission tuning for a 4l60e and a 4l80e are? As in shift points, pressure, etc. Wrong section to ask but figured I'd try

 

**Correction to what I said above. You would swap the PCM for 58x or get the electronic adapter from Lingenfelter. You can get extension harnesses to adapt your harness to the front cam sensor and side knock location of the later engines..but still a heck of a lot easier to just get an earlier engine.

 

You can load a stock 80e tune and go from there. The wiring is not the same thought. I think there's 2 wires that need switched in the Tranny plug to work.

 

You have to also add a few wires(extra VSS),you will also need a different transfer case,crossmember and driveshafts if switching to the 4L80E.