The rear of 99 02 E250&E350 well bolt right on thay have the old bolt pattern
you well to modify Ebrake cables to work
Other than the E350 is a Dana 60, and the truck is a Sterling 10.25.....lol
It is not a direct bolt on.... I am currently working on making a bracket for the rear end that would utilize the Superduty caliper and ebrake assembly, as I fell the Caddy ebrake is not up to par...
If all goes well you should be able to use the E350 rotor with the rest of the superduty parts....
I hope it all works, should be poppin out some brakets this weekend, and looking to see if my idear might work....aome welding required
on edit: I guess if you are going to swap out the whole axle, then it would work.