Hy atomarc, I was only offering a suggestion of somewhere else to look given all the facts in the post, and I have seen this before when a transmission has been over filled, that is why we only fill to the bottom of the plug on a level surface. Tailgates post said they had just completed restoring the running gear, so I assumed [and we all know what happwns when we do that] that a new seal had been installed correctly. By the way does the replacement neoprene seal fit the 216s if my memory is right I think it does.
