I have a lift and 35" tires. instead of changing the gears in my diffs. Can I have a steeper first gear intalled to get me moving a little better? Or will that even work? What does it cost to have a tranny built? Its about $1600+ to have gears bought and installed.

 

2.75:1 is *** deep as you can go with the 4L80E...I don't know if that is stock though. I think 2.52 is stock.

Let's do some math:

assuming that a 31" tire height is stock, and you indeed have the 2.52:1 1st gear, to obtain the same performance in first gear with the new 35" tire you would need a first gear that is 2.85...not an option. Granted with just changing out 1st gear, the rest of your gas mileage will stay the same. But...your acceleration problems will continue into the remaining 3 gears.

To return to a stock rev/mph ratio across all gears, you would need a 4.63 rear end ratio.

Personally, I'd just work on the power plant to increase pulling power...but I'm not exactly the most practicle individual you've ever met

 

Yeah you can install a deeper 1st gear, it sould also come with a slightly lower 2nd gear too. Sorta like putting a wide ratio set in the Ford AOD...going from 2.40:1, 1.48:1 to 2.84:1, 1.55:1 makes a HUGE difference in acceleration in those vehicles.

That will only help out your getting moving out of the hole, your lugging will still come from being undergeared for the tire size.

To build a 4L80E is going to cost a bit more than a 4L60E. The gear set alone will set you back around $500 for the 4L80. Then a full rebuild kit I'd say is going to be around $500 as there are more parts needed. TransGo shift kit another $100. Stall converter $750. $500-700 labor. You are pretty much at the cost of a gear swap. lol! But'd you'd have a badass trans!

Imagine if you did gears+built 4L80E!