I have a 91 4 door xj with a bad rear floor pan (cargo area).. The part no.# for the 91 pan is 55345663, but is discontinued.. I did find a rear pan for a 2000,2001 with a part no.# of 55175177 AD. My question is will the 2000 pan fit the 91 model ? or if there is a difference, what are they ?