After market stereo in 1997 eddie bower ford expodition provides no sound

You should be using line out from your aftermarket stereo if using the vehicle's existing amp. Then again, you may choose to bypass it, depending on the power being put out by your new stereo.
In both the Expedition and Excursion, the sound systems are different than smaller Fords. The Eddie Bauer typically had the Premium sound system, and the wiring can get tricky with those. You want to make sure it's done right so you don't short out and damage the amp circuit in your new stereo.
If all you're using is the existing speakers, then go ahead and bypass.