Funny you mention C-5..C-5 and C-4 is same thing actually AND C-5 is a little stronger. Also what is wierd and true when i had my transmission fixed last time he let me know mine was a C-5. I still call it C-4 just because alot of peeps dont know what a C-5 is and its basically samething.

so its easier then saying C-5..even though i forget about it being a C-5 most of the time.