Rear Diff ? while doing 5MT Conversion

Hi I am in the process of helping my friend do a 5MT Conversion in his '92 SVX. Everything is going great and we hope to be done in about a week.

While installing the rear differential and the rear cv axles we ran into a problem. We are using a 5spd from a 2002 RS so we had to change the rear differential. Well when we went to put the axles back in one will go in but the other will not. The shaft on the one is too long. I looked inside the original rear diff and there is a hole all the way through it. The RS rear diff has a bar going through the middle. Basically the one cv axle has one set of teeth that go into the differential and then it ends. The second axle has that set of teeth then it is about 2 inches longer and has a second set of teeth that fit into the original rear differential. We are using the smallparts kit, a huge pile of crap if I may add, and it doesn't mention anything about this at all but it may be because they expect you to use the WRX tranny that doesn't require a rear diff swap.

Basicaly I am wondering if I can cut off the extra part on the cv axle or is there another cv axle that we can get to replace it.

If this is confusing at all please specify and I can try and explain it better and I can also take some pics if I need to.

Thanks