The TDD line doesn't have the bells and whistles then the TN line has. They have used off the shelf parts where they could instead of designing new parts to keep cost down. The rear end is an old Fiat design and works fine. It just looks a little different then what most of us here are use to.
Can you get the charcoal filters for the TDD?
I personally like the TDD line and will add one to my collection when the budget allows. It looks and feels solid and from looking it over I can't see any areas where CNH
cut corners.