[curtis73]

Which vehicle? weight? torque and power peaks? cam? manual or auto? What stall? What ratios of gears in the tranny?

 

[curtis73]

Sounds like 3.70 would be perfect. One to either side (3.55 or 3.89) would do well too. There will be plenty of torque availabe so you don't want to waste it with too much rear so I'd avoid anything 4 and up numerically.