They're way different. Length...spline...etc. nothing is the same.

Your closest neighbor is the 944 iirc.

I would call someone like parts heaven in Hayward ca and ask if the splines on the boxster axels will work on the 996 hubs. We used 993 suspension with a boxster 5 speed and found that the stock boxster axels worked.

I thought axles would be hard to find. You are mostly talking 28 or 33 spline. 28 spline for the 930, 108mm CV and 33 spline for the 100mm CV. If you go with an EMPI style axle ($200 pair) they have 3" long splines so the overall length is somewhat forgiving since the CV will slide on the axle. You can take a 28 splinf axle and have it machined to 33 on one side to have a mix match of CV's.

Pacific Customs http://www.pacificcustoms.com/porsche-930-...moly-axles.html has a good selection of both types and will sell single axles for offset diff like the Boxster you are using. You will need one axle 3/4"-1" shorter than the other. These guys also sell a CV grease ring 7/16" thick that can be used to spade a CV out if your axle is too short.

If you end up with a severe angle on your axles (like me) you will need "Non Plunging" CV's with EMPI axles. The non plunging type can be used up to 40°.

I also have several 33 & 28 spline EMPI axles of various lengths. when you figure out a length PM me and I'll see if I have what you need.

If your using a early (2000 to 2004) Boxster S six speed transaxle the pass and driver axles are the same length. I suspect this is what you are using because this is the only one that Kennedy makes a adapter for the LS engine. The flanges on this take the larger 930 CV joint.
I don't know for sure what the 996 uses for the hubs, but I would guess that they are 930 size.

If you still have the G50 transaxle that was in your car do you want to sell it?