note really, with the 0.674 6th gear in the 6L50 https://en.wikipedia.org/wiki/GM_6L50_transmission with 34" tires, your at just under 2000 rpm at 65mph Engine RPM / Engine Speed Calculator
Actually Yes, I've tuned a lot of second gens both regeared to 4.56 and SuperCharged!:grin2:
If you do the math, a 35" tall tire needs a 4.42:1 gear ratio. But, you would be pushing more mass so, a 4.56:1 isnt that bad. I have a 07 Colorado which came stock with the 3.7 l5 and 3.73's. Im going to a 35" tire and 17" rims. The closest I can get is a 4.56:1 ratio. Ill be a little slower on top end but, I'm more concerned about torque. Chromoly axles are a must.