Driveshaft seal failure is identified by traces of oil leaking from the gearbox end of the driveshaft(s).

You can either do this in situ, or if the gearbox is out of the car, you do have more space!

Remove the driveshafts using this guide.

You should be able to see the fluid sitting on the seal giving an indication of the leak.

Use a screwdriver to lever out the old seal. There is a metal outer ring which you can use as leverage.

Once removed, clean up the area, and press in the new seal. You can gently tap with a blunt tool to aid fitting.

Make sure the seal is flush with the face of the gearbox.

Then refit the driveshafts: push sharply and firmly in the direction of the gearbox, and it will 'click' back into place.

Repeat with the other side if necessary.