Running 32in tires, my speedo was way off, but when I changed to 410 gears, it returned to being perfect. Probably not the answer your looking for though. Check with Ujoint, I think he offers something.
If you have ABS, then you should be able to do it through software only.
I believe Autoenginuity software will do it, but it's $$$$.
Dealer should also be able to do it with their software (but finding a dealer that knows how, may be an issue. here is the info). http://www.dieselinnovations.com/tec...Procedures.pdf
There are also a few hardware options that change the electronic pulse reading, is there a reason you use one of those?
Found this thread. I'm in the same boat as the OP in that thread.
3.55, 33" tire.
Pulled out my speedo gear and its exactly the same as OP in that thread, green with 17 teeth. Placing an order for a blue 16 teeth gear. I'll report back when its buttoned up. Its a $4 part FYI. Ford P/N DOAZ-17271-B