I went down the modification route with my 5.3 Avalanche. I put in a 3.73 and did a tune. The re-gear for you will be double expensive given that you have a 4x4. I was still not happy with the power much less the overall towing experience. I ended up trading for a 2015 2500HD Sierra 6.0 and I’m so much happier when towing. If I could do it all over again, I would have never modded and just traded. I think the sweet spot is the 2015 2500 SLE or LT gasser. Very affordable. I bought mine for around $30K and it was CPO.