Pretty sure it's been done or asked about a 1000 times, so please don't bash me..I have done quite a bit of searching but haven't really found a comfortable answer.

I have a 2007 Silverado classic crew cab 4.8 4L60e not sure how much longer the tranny will hold up, I did a fluid and filter change, i'm now changing out rusty cooler lines, truck has little over 300k I've only owned it under a year so previous history is unknown.
I also have a 2004 Yukon Denali XL 6.0..4L80e .i've owned this beast from 2006 so I know all about its maintenance history stemming 367k miles, she has seen better days, the body is rusting cut and patch, prime and paint next winter another spot shows, suspension is worn, interior is rough, motor needs valve seals and gaskets the list goes on BUT my 4L80e is a reman unit less than a year old with barely 7k miles on it.

NOW the big question, these two trucks fall into that last production run for GM on the GEN III platform, so I want to assume they share many wiring similarities, only thing I noticed up front is the pickup has E-fans for cooling the Denali is mechanical... is it plug and play if I remove the 4.8 and 4L60e wiring, TCM and ECM and replace it with a freshened up 6.0 and 4L80e, I know driveshafts and trans cross-member have to be swapped, and the LQ4 ECM would need to be programmed if I want the E-fans as well, but basically am I looking at more pull and swap with little headache, or will there be splice and guess?

Now before I get the responses of sell and buy or leave it to the pros. I was a 6097 in the Marine Corps F18 fighter jet structural Tech, very comfortable around a TIG and MIG as well as machining equipment, I've done a few swaps on European cars and Japanese and owned a TBSS for a short spun bearing period, so I'm no automotive newbie, the 4.8 lacks the grunt and the Denali is retired but will not leave with a $4K trans and a perfectly good 6.0. this combination isn't easy to find especially around New York and certainly not cheap, I just don't want to go down this path thinking I have two running vehicles so it's fairly simple to find out half way through that, I have to re-pin or splice or a major reprogram..

Thanks Folks...for any comments, directions or assistance..

 

The LR4 and LQ4 are BOTH Gen III. Everything should transfer over. Use the LR4 ECM and retune it for the LQ4. Remove the fan from the LQ4. Then the E-fans will still function.