Oh, as an FYI in big red letters.....

Avoid the 97's of either E420's or C36's. Old brain engine vs new brain tranny....down the line not the happiest mairrage. Yes, the 5 speed is more responsive and doesn't get the odd shifting ideas that occasionally go along with the 4 speed. That said....the 4 speed is a good bit more durable from what I've seen. If we are talking C43 vs 500E that is a whole other debate...

Lee