It's official.
I can no longer stand my transmission on my kick.  I have a 1995 16v sidekick and it's bolted up to a 1990 Geo 5-speed.  My original transmission was destroyed last year so i went to several wrecking yards to find another and this 1990 tranny was all i could find.  But the super low 5th gear in the early transmissions are just horrid on the highway.  And sadly i do a TON of highway travel.

Would it be better to try and find a later model 5-speed tranny and do a swap, or would it be more cost effective and smart to just swap out the one short 5th gear for a taller one out of a newer tranny.

Why not go to bigger tires? You know you want too and then that shorter 5th gear will be about right on the highway!

Already had bigger tires.  I do too much highway driving in it so i went back down.  So no I don't want to do that again till i maybe get another vehicle.  For now this is my one and only DD so i need to do something soon, my fuel expense is outrageous.

Bump.
I know someone has to have a better answer.

Your going to need another transmission to get the higher gear anyway.  I would pick up a 95+ transmission and rebuild it.  Then drop it into your existing car and sell the old transmission off to pay for the rebuild parts.

Is there really that big of a difference in the 2 trannys final drive ratio?

I believe it is 795 vs 865, so good for 500 rpm's or so when on the freeway.

500 noticeable rpms though, and actually it's probably more than that.

It used to be on my original tranny i could cruise the highway at a comfortable 3200 to 3300 rpm at 70 to 75 mph.  Now it's like 4100 to 4300rpm at 70 to 75mph.  It's loud, and just drinks gas like a full sized SUV.  I go through as much or more gas in a week as my co-workers do in their Full sized 2003 Chevy Tahoe and Hummer H3.  It never used to be that way until i changed to this transmission.

Here is a fun transmission calculator built by a friend of mine on another forum.

http://www.solemnwarning.net/transmission/

There is a beta of his new setup at http://www.solemnwarning.net/transmission/beta.cgi but I haven't gotten him to add Suzuki gear on there yet. 

I HAVE THE 95 4 DOOR KICK ON 31'S  I  AVERAGE ABOUT 17-20 MPGS WITH MINE BUT I DRIVE IT TO THE REDLINE THROUGHT THE FIRST 3 GEARS  ...  MINE HAS 155000 MILES AND GOING STRONG... EXCEPT FOR THE BODY MAYBE 95 AND UP IS THE ANSWER...