Napa and Carquest said they don't have it but maybe there's another way to look it up?
It's p/n 34982-5 (m-89-ha) in the diagram below.

Will this work?
https://www.mcmaster.com/#90636A080

 

So you just need the nut? I can send you the ones I just took off my 72 F100 in preparation for my CV suspension swap. I just have to dig through the recycling bin......

 

Thanks for the offer butI have my used ones, just looking to replace them with new.

 

SteveJH i would take the nut to either Fastenal or Tractor Supply. they should have what you need. Tractor Supply sells their nuts,bolts by the pound . they have grade 5, grade 8. and also stainless.

 

McMaster-Carr can bail you out of almost anything. Find their website and bookmark it

 

Edit: See post #8.

 

I guess I should update that, I sold my 78 almost a year ago. Right now I'm working on a 69 F250.

 

Wonderful, but you still posted the wrong picture, and typed the wrong part number.

If you look at that 1970/72 pic (click on it twice to enlarge it) you will see a black dot in front of the 34982-5 part number.

Look below for what the black dot refers to: F350

Please, when asking questions, list ALL the pertinent info. We are not mind readers!

1965/69 F100/250 2WD = Here's the correct picture:

34370-S8 .. Lock Nut-Free Running - National Fine Thread - 3/8" -24 / Obsolete

BOWMAN SALES & SERVICE in Bowman ND has 6 = 701-523-3257.

NOS PARTS LTD in Waxahachie TX has 11 = 972-937-2201.

GREEN SALES CO. in Cincinnati OH has 325 = 800-543-4959.

 

Thanks, NumberDummy. It's appreciated.

 

Ace Hardware, locally, has those in grade 8. You might try there.
But the old ones would have to be far more rusted, than what I imagine NM weather could do, before I'd worry about them.
In truth they really aren't that important. They do hold things together but it is a rather low stress area. Unless one is performing stunt jumping where the front end comes completely off of the ground.
I raised the front of one of my 72s by putting a 1/2" spacer under the lower spring plate and used a thinner swaged side grade 8 nut. The kind with the three dents on the hex flats.
Never have I seen one, nor heard of one, failing.

 

I'm not planning on ramping my truck or anything even close to that, but the threads in the nuts were visibly worn, and they came off a lot easier than I thought they should.
A knowledgeable counter person at NAPA knew what it is found them in stock. The ford part number did not help.
For posterity, here's the info on them for someone looking for them in the future:

3/4"-10 prevailing torque locknut, NAPA p/n 4767036