Novice here needs a simple class in the difference between the 741, 742 & 489 rear.
Are the guts the same and the difference only in the housing?
Is the posi section (Limited slip) rebuildable? If not, where can they be purchased separately? Any idea as to the cost?

thanks

they all take different gear set's. i believe the sure-grips will interchange. as far as rebuilding there are 2 styles, 1 is for sure and the other i've heard of them being rebuilt but don't know for sure. hope this helps, someone with more knowledge will confirm or correct me if i'm wrong.

clem

All three sets take a different ring gear and pinion. There are 2 sure grips that were available OEM. The clutch type (rebuildable with a kit) was available OEM through the 1968 model year. The auburn (spring and cone type rebuildable only with machining) came in OEM in 1969. They are interchangable from case to case with the proper side bearings for the sure grip unit. The clutch type is by far the best.

Sure-grips interchange between all 3 casting designs.

All gear ratios are available new for the 489 and 742 casting.

Only 3.55 and 3.73 ratios are available new for the 741 casting.

Check out this link for comparisons:

http://www.moparts.org/Tech/Archive/axle/1.html