Needing help selecting gears. In process of going in with a 5.3 (heads, cam, nitrous) with a 4l60 behind it. My normal run around wheels will be 20" with a 275/40/20 (28.62 height) and when at the track it's looking like I will be on a 27 or 28" radial. I was originally thinking a 4.10 but now I'm kind of wondering if I should go 3.90? I don't want to run out of gear at the track. Ordering the Tru Trac and gears today if I can get this nailed down.

Any help is appreciated.

 

With those heavy *** 20s, you'll want the 4.10s.

 

The truck isn't a daily. The 20's will literally just be for cruising around on occasion. I'm wanting to have it setup to cater toward the drag setup.

 

If it's mainly a drag setup, I'd look at 4.56s.

 

how do I figure out if I will run out of gear if I'm running a 27" tall drag radial?

 

At what RPM does peak HP occur? What do you expect for MPH out of it? Do you know the % if converter slip?

For example.... 27" radials, 4.10 gears, theoretical 116 MPH with a fairly efficient converter. My math puts that setup between 6000-6300 at the stripe. HTH

 

With that setup you will want 4.56s for the 4L80E that will come when you get tired of blowing up 4L60Es.