sub
For a direct replacement, that is cheap and no worry of being stiffed with another blown sub sent to you - go to any local pick your own part junk yard.
Take a aa battery with you and tape speaker wire to the each end. Touch the wires to each side of the terminal and you will see the sub either move down to the magnet or up and hear slight static. This will tell you if it is still working.
You dont need a SHO, to my knowledge all the JBL sub's are the same, it's just the boxes that are different. Most all the 91-94 Eddie Bauer Exploeres have their sub's in the back. Simply pop off the speaker grill and (you will have to gently move the foam cover out of the way) unscrew the sub from the housing (4 screws) and unplug and away you go. Most of the explorer subs have an additional plastic grill built on to the sub itself, but that shouldnt affect the sound or fit.
Good luck.