Your right. I just looked it up. OBD-1 started in 1988. OBD-2 was required to be in place by 1996.
OBD-2 standard was created in 1990, but wasnt required until 96. I just assumed all powerstrokes used obd-2.
Now, technically, the powerstrokes are NOT required to meet OBD-2 standards until 2004. THis is why most generic code readers have problems with vehicles over the 8800 lb limit of OBD2 requirements.