I have a 1998 SS with the 3:42 rear end.
I'm looking for a little more low end and was thinking about changing rear gears to 3:73 or 4:10.

I have a 6 speed manual trans and now only tach around 1500 at 60 mph.

If my calculations are right I shoud be taching about 1640 at 60 with 3:73 gears or 1800 with 4:10 gears.

I don't feel the 1800 rpm at 60 mph seems too steep????
How much diffeence will I see in gas mileage?

Just wondered if someone else is running this set up...

Also someone stated that I need to reprogram the car if I change gears.........is that correct?

 

I'm not running that yet but I am going to be soon. 4.10 will give you lots of get up and go. You will notice a few mpg loss but nothing to bad. And you just need the car programed for the new gear ratio. That shouldn't be to pricy and won't take long to do.