Audio Systems: lincoln with alpine system, wattage ratings, alpine sound

Question
In the 2002 Lincoln ls with the Alpine sound system, what is the reccomended rms/peak wattage for the rear deck speakers?

Answer
Wattage ratings on loudspeakers is not so useful.  You can connect any power amplifier if the impedance is matched and the loudness control on the amp is properly controlled to feed the speakers power below the distortion or overdrive of the speakers.

Your best solution to this may be to go through the "outfit my car" sequence and let it guide you to replacement type speakers that would represent the size, wattage and installation of speakers.  You can google those words and it will take you to a site that will work you through to answers to the questions you ask.

Hope this will suffice.

PS:  Peak wattage is merely 2 times the average continuous power ratings.  But, technically speaking there is no such thing as rms power.  We use rms for voltage and current but they yield average power not rms power.  There are no universally accepted power measurement standards for speakers like there are for amplifiers.  It is very subjective.