I'm building a vortec 350 with around 380hp. I'm replacing the rear end soon. What gear ratio should I go with? This is my daily driver and it's a 5 speed. It currently has the stock non posi 3.08 gear in it now.

 

I hear a lot really enjoy their 3.42's. If you'd like even more bite that shouldn't cause problems being a daily driver, go with 3.73's.

 

I think best all round is 3:23 / 3:27. With that power plenty of acceleration and lower high speed rpm.

 

With my 350/330 and T-5, I like 3.23's, which seem well suited for both town and highway driving.

JamesC

 

3.23 if you have the .73 fifth gear. 3.73 if you have the .63 fifth gear. Both setups spin the same rpm in 5th on the highway.

 

Agreed and I have run both combos. 3.73 with a .73 gives lots of acceleration on the expressway but MPG suffers bad

 

It really depends on what kind of driving you do more of - highway or city. My camaro had 3.42s in it stock, and they were nice as an all-around gear, but I really like the 3.73 i swapped in a couple years ago. I don't do much highway driving in my camaro though, so highway mileage isn't as important to me. If it was, i would have kept the 3.42s.

 

3.73 puts you at 2500rpm at 75mph. Works for me. You can trap 120-125mph at the top of your 1:1 ratio around 6500rpm.

 

Either of these would be a good compromise. My son's GTA has the .73 fifth with a 3.45 axle. Performance on the highway is excellent (no downshifting required), but the motor spins just a little too fast, feels like it needs a sixth gear.