I checked the manuals I have for my '09 5600 and could not find any alignment specs. Since these machines have 4-wheel steer capability I would suspect the the tires should be parallel so the machine is not fighting itself when in 4WS mode.
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Front & rear both have a slight toe adjsutment. Attached is the procedure and spec. this is for all 5610 to date and 5600 with 4 wheel independent suspension. Not for A,B, or C series with straight axle.