It's just that northstars are so expensive. So it would technically be possible to mount a 5.3 in the gxp?

Okay fellas this is just a brainstorm. I drive a 2005 gxp and i love it, but i have about how the northstars have some problems and they are a pain to work on. So lets say i blew my engine and i wanted to swap it, would a 5.3 fit and would it mount up to the 4T65E? what would be the best engine do a ...

I recharged it and it says it's fine, the compressor turns on but I haven't checked the pipe yet

my air conditioning only blows hot air, I checked all the fuses they're fine, my dads friend said it might be the blend door but I wanted ask around to make sure.