Mirrortints is correct clear clean photographs will help us help you, but regardless to the fact of be it the 6.5" rear deck mounted subwoofer OR the 8" rear facing subwoofer mounted into an injection molded plastic sealed cabinet... The both are DVC (dual voice coil) subwoofers so either you're reconnecting a CUT 4-Wire harness (assuming the plug is still attached to the 8" sub cabinet) or stripping and soldering leads to the 6.5" sub it's simple.
But you must know the polarity of the wires and woofer if it's the 6.5" as for the 8" if the pig tail is still attached to the plastic box then match the wire colors together and done. Strip Connect Flux Solder Heat Shrink viola...!
But a good clean picture is worth a thousand words and since you're standing in the need I'd suggest a few pics hit us back pal,