I've bought all my seals from C&C which have been really good quality and fit.
The tailgate seal has been on for the last 6 years without any problems.
I used the Vewib rubbers when replacing all on my van.
The van has been out in some horrendous rain, however, no leaks. Where possible i also put Dinitrol Waxoil on the body where the rubbers sit as a precaution.