In the Ford F250/F350 series, what does SR, DR and DNR mean?
I have a 1983 F250 HD 4X4 SLT Lariat
with a 460 7.5L, pre EFI. My truck was a
special DSO. In looking at brochures
from 1983, I now see SR stands for
Super Duty. But can found nothing about
what DR or DNR mean?