I need a rear axle housing to fit into a 1989 5th Ave. Obviously Diplomat/Gran Fury/Aspen/Volare (1980-1989) should work. The ratio needs to be 2.94 to a 3.21. Mine currently is 2.71. Even though this is an "M" body I have used an Aspen rear axle assembly before and it bolted right in. Thanks.