I have a 2003 E350 that has about 125000 miles and is just running wonderfully. We have really tried to take care of it as had the previous owner. We are planning a long vacation in the van and the question of when the timing chain needs to be replaced so we have no problems. I can not find anywhere a recommendation for that in the manual. Does anybody know what the recommendation is for the timing chain. I would hate for it to break and mess stuff up if I can prevent that now.

 

I wouldn't worry about it breaking, they don't have a history of doing that.
I have heard of some wearing and causing problems related to late timing. Depending who does the job if you decide to go ahead with replacing it, might get into the picture.
The 03 -5.4 engines in the 350s were pretty reliable. Keep asking around and you should get a better feel to make a wise decision. Have an experienced Ford technician check it out that might help with your decision.