I doubt it. I've never seen a F-350 with P/S. I have, however, seen quite a few F-250/F-350's with P/B. I don't think you need it though, with alot of weight in the back it steers/rides like a caddy!
A customer's '67 F350 has PS. I can't swear to it being stock, but I can't see why it wouldn't be. An old one ton dually needs PS more than an F100 any day.
Mine has armstrong power steering. Keep air in the front tires, and don't try to steer when you're not rolling and you should be OK.
This is another item that can easily be taken from that same '73-'79 that you get the front disc brakes from. http://www.fordification.com/forum/view ... hp?t=35239
Steve
1970 F350 DRW Factory 9' Platform/Stake, 360, T18.
Passed on to new care taker July, 2013