is there another way to tell the inboard size of cvaxle without removing old axle
I don't know why you are focused on only the inboard axle dimension, but you could refer to it in the Bentley manual if you have one. Those books are great to have, but not cheap. However, I strongly recommend replacing the axle and joints as an assembly rather than attempting piece-part repair. It costs less, saves time, and allows for a decent warranty due to quality control at the vendor. If you are looking to upgrade your axles/joints to allow for more power handling, I'm pretty sure the stock axles are fine for up to 300hp. If you need more information, I recommend signing on to one of the VW forums out there that focus on MK2 VWs.
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