A lot of experienced mechanics don't torque the bolts - they develop a "feel" for the right amount of pressure - so I suppose it isn't absolutely necessary.

Still, a torque wrench is the only way that you will obtain an objective, accurate measurement.

Torquing to the right specs ensures that you aren't over- or under- tightening - pretty critical if you want to do it right.

Not using a torque wrench means you are taking a chance. If you get in the correct range, you won't have any leaks - if you don't, you may develop leaks over time, either through over- or under-tightening.

Your truck, your choice.

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2003 Supercab Flareside
4 liter V6
4x4 FX4 Level I
5 speed Auto
4.10 LS Rear