Today my transmission has been slipping around 40 mph. It slipps like it is in neutral and then jerks into gear as if it were catching. However, the problem does not occur when when I turn overdrive off. Any ideas? Could it be the transmission valve? Also I read it could be a snap ring which I'm not really sure what this might be.

 

I would also like to add my issue to this one. I am having a similar issue. After having these symptoms and having the tranny completely rebuilt, the symptoms continued. Ultimately the valve body was replaced (bad selenoids?), and its started again, 1.5 yrs later. These symptoms are not easily diagnosed because they do not happen consistently.
Under warranty, but tranny shop says they cannot identify the symptoms and claim to have pressure tested the hydraulics and all checks out fine.
I am determined to get this repaired by them under warranty, but I am at a loss due to the inconsistent sysmptoms and diagnosis difficulties.
Looking for any help I can get!!!