There is no rhyme or reason as to the order trucks are built. 4 weeks in D1 is not very long honestly. My 3500 HO DRW sat in D1 for 8 weeks, then was built and sat at the outside vendors (JB) for 8+ weeks for still unknown reasons (I think it was just partying too hard and enjoying Margaritaville), before it even went KZLD. I lucked out and found a train ride 4 days later, and now it sits at Port Allen waiting on a trip to the dealer. To date it has been 21 weeks, or 146 days, and again, I am one of the luckier ones - there have been some waiting since last year that have still not taken delivery.
As I have said many times on this 5+ month journey: Saddle up, buckle up, and enjoy the ride