Clarkie GT

After changing my rear diff due to changing to a UK spec gearbox im struggling with the drive shafts... My current shafts have the snap rings but the new diff has the rings also. So if I simply remove the rings from the shaft and fit the shaft, will the recess/cut out in the shaft line up with the snap ring in the diff?

I think I've either damaged the snap ring in the diff trying to fit a shaft with the snap ring already on or the offside shaft needs to be longer as I can fit the shaft with out a snap ring fine and it fits but 5 miles down the road the shaft will pull out the diff again, although the near side is fine.

Any body had any experience with this?

Oh, and the car's a 95 WRX V2