I rode in a friends truck tonight (03 Z71 w/5.3 and no mods) and must say I hate my 3.42s. I don't know whether Z71s come stock with 3.73s or 4.10s, but his truck had as much pickup as mine does, and I have a tune, intake and exhaust (granted, the SS 20s don't help my case). Either way, I'd like to swap out to 4.10s and a trailblazer converter, but I don't want to ruin my relatively new tranny or warranty. Would the OEM 4.10s and TB 'veter give me problems in either of those areas, and how would it affect my mileage? I don't drive like a Petty (typically) but I want my truck to at least have a bigger jump than a heavier, stock 4 x 4. What kind of costs am I looking at, including installation?

 

Your gas mileage is going to suck at first then you will get a little used to it but will sticll suck. lol IMO any ways. I have a 3k verter and 3.73s and (probably) get 14 mpg on a really good day. Not sure about installation cost though, me and my boss put in mine. The gears will run about $150-$200 and installation kit will be about 130 bucks.

 

yeah, just had a TC installed 3K from tci (454.99) shift kit from transgo (129.99) right about 7 and some change installed


also 3:73 and eaton posi both from Randys ring and pinion (700 installed)

 

I will have some 3.73 gears really soon. You will be suprised what just a locker will do for you though. Gears are great but if only one tire spins then it doesnt matter. It takes more torque to spin BOTH. therefore better acceleration if both have traction and DONT SPIN