Take care you get the right one. Wrong way round one way, and the shaft will never center up as the cups will not be up against the circlips, ie, the cross piece is too small across it's width.
The other way, you'll never fit them, as though the cups are the same diameter, the cross piece is larger across it's width as it were, so you can never get the circlips in...
Either way, it doesnt work.
Best strip out the damaged/knackerd joint first, and take the (now free and cleaned up) drive flange part to the shop with you, so you can check you have the correct UJ to fit.
Many vehicles do not have the original propshaft fitted, so can often catch out the unwary owner doing this DIY...
How do I know? I just had to change one myself, and the first joint was too big, wasted fiver... The correct (smaller one in my case) cost £15... Just my luck...
Job done now anyhow...
Enjoy..
Dave B.