Did Chrysler ever put A 7¼-inch rear in the 1987 Grand Furys with 318 motors or were they all 8¼˝ rears? Is the yoke on that ’87 Grand Fury the same as a cop car if it is an 8¼˝ rear end? How can I tell if I have an 8¼˝ or a 9¼˝ rear end? Mine went out and I have a friend who has an 8¼˝ out of a cop car that I can get. Oh yeah, I almost forgot what the hell was Chrysler smokin’ or doin’ when they put these corporate GM rear ends in these cars? Anybody with any brains knows that these rear ends were junk to begin with when GM first started using them. Even their most popular rear, the 12-bolt, was not that good either. I’ve seen and heard about them down through the years. They were all junk.
Some M-bodies were, indeed, 7¼˝ equipped, and they have the identical yoke as the 8¼˝. If the cover is retained by 9 or 10 bolts, oval w/flat bottom: 8¼˝. 12 bolts, octagonal shape: 9¼˝. There’s not one GM part in these, the design is 100% Chrysler. They were built at Chrysler’s Detroit axle plant. Both are excellent axles, the 9¼˝ is plenty strong enough for a typical 9-second car, and the 8¼˝ is adequate for most mid- level smallblock cars. They are both extremely easy to service, too. See “Revolution No. 9¼˝ in M.A., June, 2012, for a beefy 9¼˝ buildup, and “Dak at the Track” in Feb., 2009 for a similar deal for an 8¼˝. I would agree that the 7¼˝, which first saw service in the 170 CID 1960 Valiant, is pretty frail and flimsy. If you swap axles, don’t forget 7¼˝ car’s propshaft is 1.35˝ longer than the one required for the 8¼˝.
