I had the third version installed in the forward position and it leaked like a mofo! Got in touch with APT and they admitted there was a problem and sent me the new version IV (they were really good about it even tho I live in Australia) I have now installed the new one (this time in the rear position) Drove for around an hour and had zero leak. I did take photo's to show what the new seal looks like but I lost my phone
an easy way to tell is that the new seal is a more square/rectangular shape and it covers the shoulder on the ball, where the other round seal did not. Hope that helps, can't do much more without the pics