I have a 2000 E150 that has a 9.75" 3.55 LSD rear axle that has drum brakes. I'm looking for the same axle but with disc brakes. The axle code in the door sticker is H9 which would indicate an 8.8 rear axle so that's not much help to me.
This table shows you should look for a C9 axle code. And it also shows the H9 which matches your van. Don't remember where I got the table, but I keep it in my OneNote for van stuff.
I'm looking at that option as well. If I can find a salvage rear axle with disc brakes on it for a decent price it would be a perfect opportunity to go through everything and end up with a completely fresh rear axle assembly. Could also be an opportunity to change gearing from the current 3.55 to possibly a 3.73 or 4.10.
Interesting side note: I asked about doing a brake upgrade in another sub forum and got a reply about just doing an axle swap. I ask about axle codes here to do an axle swap and got replies about just doing a brake upgrade. Not trying to say anything negative just laughing at the irony. I do appreciate any replies that provide solid info or provoke thought from a different perspective.