rear diff

[79aspen]

wanted rear diierential from early 80s cop diplomat with limited slip
need it for 79 aspen

 

[Dr.Jass]

hey're easier to find than you think, 79. Chrysler built about a billion of these axles. They used that axle from 1969 well into the '90s in everything from A-bodies to pickup trucks (both full-size and Dakotas).

Virtually any 8¼" Sure Grip will work, with the following exceptions:

• All 8¼" rear axles use a 10-bolt cover and have straight 3" axle tubes. There are 10-bolt 7¼" axles out there with 10-bolt covers, but the axle tubes neck down to 2½" before they enter the center section. My '84 Fifth Avenue had one of these bastards originally.
• Axle-shaft spline count changed in the middle '90s ('97 if memory serves), so seek out older ones.
• Check the gear ratio, as the Sure Grip unit for cars with 2.2- and 2.4-series gears used a different carrier that can only be used with those ratios. It cannot be made to work with any other gear ratios. The diff you want will have a ring and pinion ratio of 2.71-4.56, though Chrysler never installed anything wilder than a 3.92:1 gear originally.
• Check the cross shaft's fit in its bore before you buy. Chrysler cone-type differentials are notorious for ovalled-out cross-shaft bores. The shaft should be absolutely tight in its bore... no play whatsoever.
• If it's still installed in an axle, jack up one side of the car with the trans in neutral and do your best to turn the wheel not on the ground. If you can do it easily, pass on it as the cone clutches are shot. I have not yet found a reliable method of repair for this on the 8¼".

Don't put too much money into this axle if you're going to throw more than about 300HP (a real, dyno-proven 300HP) at it. It's not a very strong axle. Personally, I wouldn't use one just because of the C-clip axle retention. I watched an axle walk out of a really-nice original 340 Dart Sport and completely destroy the quarter panel. Heartbreaking.