if you see a new rad support listed to fit a diesel,then the sellers info is incorrect.if you order from anywhere (other than NOS from some ford dealer) a new diesel rad support,then you can expect to receive a gas support in the mail.fair warning.
if i had to replace mine,i would just buy a gas one,and take it along with my old diesel one to the local metal fabrication shop here in town and have them cut out the lower section and fab up a new diesel sized lower section for me.
it's just got to hold a radiator.it can't be that complicated to copy.doesn't even need to look the same.as long as it does the job.a little metal and some welding and done.