Hi Frank, from what I know there is basically no difference externally between these 2 boxes. The 65 is, I believe, the later box and it has slightly better internals. The only other difference that I know of is the layout of the selector. The later 65 box has a layout of P R N D 2 1. Think I've got that right. Have you checked the following:- A) The fluid is in good condition
B)The fluid level is correct
C) Basic settings are correct
D) Engine is in a good state of tune
Hop this helps you Frank

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