I did a bunch of Google searching for the "J" Hook Wiper arms last night, probably spent way over an hour reading different threads, web sites, what E-bay posts etc...
There is a lot of after market stuff out there, mostly Chicom stuff, but then there isn`t any NOS, OEM stuff left, unless some one has it on a back shelf in a wear house etc...
I did come up with one part# F1TZ-17526AA that fits on 91 - 97 F-150 - F-350 and Bronco.
Then from Lakeland, Ford in FL. they show for a 97 F-250 F4TZ-17526A for $24.97 each arm, special reduced price.
Phone # 863-577-5010
Ford seems to have used the same size Splined Shaft for quite a few years.
Then is seems (from reading ) Ford made the splined shaft a larger diameter on the new stuff they are making today, but don`t know what year they did that. Guys on that thread were not real clear.
Did some poking around on Rock Auto.
"J" Hook 21.75"
Pin style 18.75"
Looks like 90 was last year for the "PIN" style
90 first year for "J" Hook.
97 shows 2 different Arms.
Front left 24.5"
Front 21.75".
Also these use a Splined Flange Nut.
So looks like we are good up to 96 for the "J" Hook.
Do your own searching to be sure.
Goat