I have been wondering about this myself. Searched and didn’t find anything on the forum. I don’t think you will find any van-specific 5.4 headers out there. I did some digging and found that the excursion 5.4 and other 2valve 5.4 application exhaust manifold is the same part number as the van 5.4. (See compatibility at the bottom of this page at O’Reilly
I did a bunch of looking around at summit
and found the Gibson GP126s (and 126s-1 not sure if EGR or not) fits the excursions and pickups. I called Gibson late last week, but they wouldn’t commit to it fitting the vans. I felt like I got blown off a bit, but he said that he didn’t think it would fit because it would hit the firewall. I haven’t crawled under there to look again, but I don’t remember tight clearance around the manifolds. So, I’ve been thinking about how to figure this out.
One reported downside of shorty headers like this is a loss of low-end torque, but the Gibson site does a good job of of marketing and saying they create usable torque. Some of the v10 guys have headers so it would be interesting to hear their thoughts.