I have an oppurtunity to purchase a 97 tracker, 4 dr., 4 wd, 1.6, 16v, 4 spd. auto in good condition other than a bad rear end.  I have a 95 Tracker, 2dr., 4 wd, 1.6, 16v, 3 spd. auto parts car.  I would like to replace the 4 dr front and rear end with those from the 95 2dr.  From the Zuwharrie FAQ it says 4 dr. = 5.125 ratio & 2 dr. = 4.30 ratio.  The vehicle will be a daily driver with OEM tires.  Is this a direct swap?  Any thoughts on mileage and driveability in town and highway?  Are the differential/axle assemblies load rated the same?  Equal width?  Thanks for your input and knowledge.

Well, your speedo's going to be off quite a bit.  You'll be going faster than the speedo shows.

How much faster?

50 on the speedo will = 59.6 actual.

That's about 20%

To correct your speedo, you could swap the speedo gears between the tcases.  The tooth count is different between the two, to compensate for the diff ratio differences.
I would say just swap tcases....it wouldn't really be any more work, than tearing apart both tcases to swap the speedo gears.  The problem with swapping the tcases is the spline count on the tcase rear output shafts are different between the two, so you would have to swap the slip yoke portion of the rear driveshafts.....which isn't a big deal, since they both use the same ujoints.