How does the the speed sensor work in our trucks? i know its in the rear-end and that it reads the rotaion of the ring gear. The real question is if i swap say an Allison trans in place of the E4OD, will my speedo still work correctly?

 

as long as the wheels are spinning, it will work. there is a post around here that will show you how to re calibrate it for differnt size tires

 

What allison do you plan to swap in?
I sure hope not a duramax one.
They are only rated for 350 hp.