Or I could change the tire size with the SCT from 32" to 26.95" and it would yield the same rpm on the rearend, at least in the ecm's mind.

 

The SCT option won't work for 03-04 trucks because they can't flash the ABS. The 05 and up trucks use the ECM for the speedo. I was told that the speedo will read the same if I change the ratio because it is just reading revs per mile off the tone ring, so it doesn't matter if I have a 2.70 or 7.20. Now I'm learning that the tone ring will only work down to a 4.30 because any ring gear lower isn't machined for a tone ring. Basically 4.30 4.88 and 5.13 (I think) are for Ford rear ends with tone rings. If this is the case I wonder if a 4.10 ring gear can be machined to accept the tone ring?