Hard downshift into 1st gear when towing
 

Well just like it sounds. Every once in a while when im towing (which is everyday) when everythings up to temp, ill be comin around a corner in a neighborhood (real slow) and it CLUNKS down to first gear.. Anyone have this happen?

is it in Tow/Haul Mode?

My truck has done this since new when in tow/ haul. I don't think it is that big of a deal. Never done it w/o the tow/haul off.

It can't clunk on a downshift with the tow/haul off. The mechanics of how the trans works won't allow it. The design of the trans makes clunks on a 3-2 coasting downshift almost inevitable. You cannot feel the 2-1 downshift. It's impossible.