Alright, I've tried to figure this out and haven't found anything in the way of definite facts. How can I tell without taking it apart whether my 8.25 rear axles are 27 or 29 spline. It's a 2000 XJ with 3.55 gearing and the tow package.

 

If yours is the original one it's 29 spline. Change over from 27 to 29 took place in late (?) '96. My DOM is 8/26/96 and it's 27 spline.

But to answer your question on how you can tell without pulling an axle. Cruiser posted a pic of two rear yokes awhile back that although he couldn't confirm it could have been one from a 27 spline and one from a 29 spline. My XJ was in the shop at the time so I couldn't check it out. I'll try and find those pics. Forgot all about it.

You ever seen this:
http://forum.northeastjeep.org/index.php?topic=1419.0

 

Not until now. Thanks, that answers my question. I'm looking at a Lokka automatic locker and needed to know.

 

97+ will have 29 spline. I've heard of some people with late production 96s that have had them.

 

Yeah, my 2000 WJ was built in AUG of 99 and marketed as a 2000. Some parts are 99 and some are 2000. IDK if this is normal or not, but the WJ's gas cap has to be turned about 2 and a half turns to tighten whereas my 2000 XJ is 1/4 turn quick on-and-off cap.