Socal-burb75

I I just took my suburban in to have the rear end looked at after I heard some sounds poping when I stated from a stop. It turns out the the quicky oil shop that I had replace my oil and change my rear dif oil didn't add the addive. well after thinking it over of just having them fix it, I desided to have them change the gears to a 3.42. I do a some light towing (jetski & trailer) and 4 to 6 people plus everything you need to go to the river, L.A. to Laughin. 275 miles. My thought was changing the ratio will help with towing allowing me to keep my speed up a bit better up hills, when im up load. My question is should I have gone with a 3.72 Gear ratio?And do I need to retune it? 5.3L 4x4 2010 LT