Mopar Action On-line – Tech Questions


Tech Question

Stephen Szanto, Melbourne, Australia, 1970 Dodge Charger 500 383

I have a 489 casing in my diff. Can this be interchangedwith others? I don’t want to change tail shafts if I don’t need too.Waiting for your answer, Stephen.


Hmmm. maybe there’s a slight terminology difference down under. In the US,the carrier / casting – the #489 thing – has the differential and ring andpinion as the main components – not the other way around. So, using ourterminology, your question is nonsensical. Therrefore, I’ll just make a fewgeneral interchange comments for you that will, hopefully, answer yourquestion:

> Any 8-3/4″ carrier (the drop-out ‘pig’) can replace any other, limitedslip or not, either / or. Except for the obvious width differences, all1965-’74 axle housings are basically interchangeable, too.

> Thre’s 2 different U-joint (and yoke / flange) sizes, watch out for that.Conversion U-joints are avaialble if you have a mismatch.

> Any 8-3/4″ differential can be used in any carrier (pig) as long as thebearings which are correct for that differential are used / retained.

> “Tail shafts” is a phrase often used here to describe the transmissionextension housing and mainshaft or output shaft. But, from the way you’vephrased it, I think you are referring to the axle shafts (half-shafts). Ifso, all 8-3/4″ rear have the same axle spline. There were very slight lengthdifferences between Sure Grip and non-Sure-grip axles on pre-1965 (taperedaxle) housings. Hopefully, you don’t have one of those retrofitted into your1970.

> Be sure to re-set (adjust) the wheel bearing endplay when you’re done,using the right side adjuster. Go for approximately 0.003-0.005″



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