Fair 'nuff. Only ordered the once from them, and it was fine. A possible alternative is a Tamiya part:
53970 Ball Differential Protective Seal. Doesn't explicitly list the 416, but looks pretty close and may be easier to source.
Phil.
Actually I've been using those on the 416 with no problems, only reason I was looking for the Jaad seals is they are made from a thicker material, a lot easier to install.