# of axle splines

[73chgrSE]

I'm shopping differentials and i notice that some are for different # axle splines. How many do I have with my stock setup? 73, 8 3/4 489 case with 2.76 open diff. 

[mikepmcs]

489 case only came with 29 or only 10 spline yokes

If the pinion nut takes a 1 1/8 socket, it is a 10 spline. If the pinion nut takes a 1 1/4 or 1 5/16 socket, it is a 29 spline.

swiped from moparts tech archives.

v/r
Mike

[John_Kunkel]

The OP asked about axle splines; all 8 3/4" axles have 30 splines unless the carrier is changed to aftermarket.

[mikepmcs]

Oops,
Thanks John for setting me straight.   

v/r
Mike

[73chgrSE]

Thanks.

[73chgrSE]

Do i have a "fine spline" pinion? I'm looking at ring and pinion gears and one says it's for a 8.75 w/489 case with fine spline pinion.

[mikepmcs]

Actually I now think my first post is relevant to the question you just asked.

v/r
Mike

[73chgrSE]

Well, unless that's visible from the outside, i'm not in there to see the nut size, are there any other ways?

[mikepmcs]

Exactly.... the pinion nut on the outside of the yoke. Now I'm starting to second guess myself, but you take a socket as mentioned above and fit it to the nut on the yoke and then you will know your pinion size by the information posted above.  You will most likely have to move the driveshaft out of the way.
Maybe the 7260/90 ujoint dealy plus the measurement of the yoke gives some idea too but this is the way I did mine when I changed my pig last year and was wondering the same thing.

http://www.moparts.org/Tech/Archive/axle/9.html

http://www.moparts.org/Tech/Archive/axle/11.html

v/r
Mike