This might be a stupid question, but what is the benefit of getting the performance axle if you have an A6 transmission?

Most non-Z51 automatics I see don't have it, but GM offers it as an option.

 

Supposedly, faster 1/4 mile times and faster 0-60 times.

..GEAR......Mode..or..Option
............Z06...Std.6-spd...Z51.6-spd...6-spd.Auto...4-spd.Auto
..1st.......2.66....2.66........2.97.... .....4.03........3.06
..2nd.......1.78....1.78........2.07.... .....2.36........1.63
..3rd.......1.30....1.30........1.43.... .....1.53........1.00
..4th.......1.00....1.00........1.00.... .....1.15........0.70
..5th.......0.74....0.74........0.71.... .....0.85
..6th.......0.50....0.50........0.57.... .....0.67
Reverse.....2.90....2.90........3.28.... .....3.06........2.29

Axle Ratio...3.42....3.42........3.42....2.56 (or 2.73)..2.73(or 3.15)


Gear Ratio times Rear Axle Ratio
..GEAR......Mode..or..Option
............Z06...Std.6-spd...Z51.6-spd...6-spd.Auto......4-spd.Auto
..1st.......9.10....9.10.......10.16.... 10.32 or 11.00...8.35 or 9.64
..2nd.......6.09....6.09........7.08.... .6.04 or 6.44....4.45 or 5.13
..3rd.......4.45....4.45........4.89.... .3.92 or 4.18....2.73 or 3.15
..4th.......3.42....3.42........3.42.... .2.94 or 3.14....1.91 or 2.21
..5th.......2.53....2.53........2.43.... .2.18 or 2.32
..6th.......1.71....1.71........1.95.... .1.72 or 1.83
Reverse.....9.92....9.92.......11.22.... .7.83 or 8.35....6.25 or 7.21

 

I wish I had a performance rear. At age 63, mine gets tired after about two hours of sitting.

 

I have it, cheap performance mod at ~400$

 

Notice the differences in gear ratio spreads between gear boxes. The
Z51 6 speed has a 31% drop between 1-2, 2-3 and 3-4 gears. This keeps the rpms in the power range without dropping into a lower power band. As compared to the 6 speed auto, 1-2 gear has a 42% drop, 2-3 drops 35%, 3-4 drops 25%. The most significat number is 42% drop from 1-2 gear wihich can hurt 0-60 times or on a track where tighter gear ratios are needed to pull out of turns. That is why close ratio transmissions are a benefit in track competions. The differential gears will change the overall torque multiple number of gears, but the transmission will give you the gear spread ratio.