You do not need to change your axles... The splines are the same otherwise I couldn't be enjoying my LSD while driving my P5 on a daily basis for the past couple of months. I did not change the axles when I bolted the MSP tranny right in the P5.
I did however need a MSP clutch disc (I was told I did because the output shaft splines are slightly larger on the MSP but to tell you the truth I have my doubts, anyway I had purchased the MSP disc and the bearings too so the new stuff just went in and I didn't even try the stock p5 disc on the MSP spline, I should have.
There is one more difference; NON-ABS cars swapping TO an MSP tranny will need to devise some way of getting speed readings because the LSD does not have a toothed ring on it to drive the mechanical speed sensor (not required on ABS models as the speed readings come from the front ABS sensors which seem to work even though I disconnected the ABS fuse in an effort to make this thing a bit more of a driver's car.)
But I digress...
