What gears are factory and what should I run ?

[Jonpen]

GM under-gears nearly everything they make - trying to satisfy CAFE MpG tests and avoid fines.4.10 would DEFINITELY be better - city MpG would improve, enough to overcome the highway MpG penalty, at least for me.If 4.10 is 'more equivalent' to GM's OE gearing, then 4.56 would be better.

I went with the 4.56

 

[AJMBLAZER]

Yours the 4 speed automatic or 6 speed?