Engine Swap

Well, there are a few changes you would need to make. Engine and transmission along with the control modules from the 5.3 and any of the modules that have the VIN in them like the entertainment systems and such. Plus, in this case the 6.2 is a more reliable engine than the 5.3 unless you make changes to that engine. What is the reason for the swap?

Had a DOD done on this engine. One month later oil pressure dropped. Low-end knock started. I've had a 5.3 in three different trucks with no issues.. Want to install a low mileage 5.3 if possible.

I've seen both have issues. The biggest thing with a swap is that half of the electronics are VIN locked so changing the powertrain module only isn't really possible because of the VIN mismatch. The VIN, however, also tells the PCM which engine and transmission you have and sets up the programming for them. So, if you just take the 5.3 part and code it to the current VIN it will try to run the 5.3 as a 6.2 plus things like security and even the factory stereo uses the VIN to work. Not saying it's impossible but in modern vehicles it isn't fun. What might work better would be to find a complete 5.3 set-up in another truck and swap over all the pieces but doing that it might be easier and less work to just find a replacement vehicle.