I would suggest getting the part number for the stock Ford steering stabilizer for your truck and cross referencing the other trucks (like an F-350) to see if they are the same part number. If they are, then order the corresponding steering stabilizer for the more common truck. You didn't list the specifics of your truck (I assume it's a 6.7, but is it 2wd or 4wd, etc) to look it up either. I went to Rock-Auto to find part numbers and they seem to be similar to the F-350, but not in all cases.
From what I could find the part numbers were the same for a 2011 F-350 6.7 4x4 and a 2011 F-450 6.7 4x4. Which would mean a 24-196284 Bilstein steering stabilizer should fit. Key word on should...
I have a stock unit from my F350 at home, if you can measure the compressed and extended length of the stock unit on your truck, I can compare it to the one I have at home. if they are the same, I would think anything that fits and F250/350 should work on the F450.
That said, I have a lightly used bilstein 5100 at home I'd sell cheap if you want to give it a go.