I have a 2001 suburban 2500 4x4 build with lift and big tires, I am considering lowing differential gear ratios, to maybe 4.56 with a 6.0 and 35 inch tires (has 3.73 now). I noticed the first gear in the 6 speed is much deeper and would be much peppier on the street and a lot better at off road crawling and towing. may not even need to regear, and if i do, it could yeild even more performance. I have 108k miles on the truck, not a-lot for a 4l80e I hear. Im just wondering what usual lifespan is, with 30k mile trans services, and how much effort is required to swap trans maybe down the road to the heavy duty 6 speed. Any imput would be appreciated!