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why would you want to shorten it? wouldnt you idealy want more of a wider stance for more stability?


Typically, you need to shorten one side to get the axle centered under the truck, depends on which vehicle the axle was from. Here's an example:

http://home.4x4wire.com/erik/4runner/sas/#Axle

While wider is generally nice, having one wheel sticking out 4" wider than the other side doesn't work too well. Also, you need to figure in covering the tire for street legality, too.