i have a 98 sidekick sport 1.8L and
i was wondering it says 33" with 4.62 gearing
would i still be good for highway if i used 5.12 gearing?
and this undertaker is in affect all the time right? not just in low range..

.Dml-

Yes, the undertaker is a full time reduction box.  I think hitting a gear calculator is going to be your best bet for deciding on gearing.   It will allow you to see how far off the gearing is.  Or you can just divide the two together to see how far off you will be from expected gearing.

For example, if your gearing is supposed to be 4.62 and your running 5.12 you will be 10.8% off.  So you will be 10% fast on your speedy.

here is a good gearing calculator : http://www.grimmjeeper.com/gears.html