Since new my truck has had the tendancy to shudder when coasting down from gear 2 to 1. It is more pronounced when coasting to a stop while decending a grade. It will do this whether thransmission is hot or cold. Does anyone know what causes this?

First things to check are the driveline and fluid level. Make sure the slip yoke is lubricated. Also, have you changed the spin-on filter recently?

If all that's OK I'd have your dealer verify that the engine and transmission have the latest programs. Then I'd have them reset the TAPS for the 2-1 shift and see if it gets any better. If not, it could be a sticky valve or a tear in the C5 piston seal.

Fluid, and filter fine. It's done this since there was 6 miles on the clock. how would a tear in the C5 piston seal cause this?