Slotted hex nuts

I have two idler arms with bolts. The slotted nut on one of them has 6 slots, the other one has 3 wider slots. Been trying to find the difference between them (other than the obvious number of slots) but can only find information on the 6 slot nuts. Can someone clarify what the difference is (again, other than the number of slots) and what applications they were typically used on?

As a general rule, 3 slots is OEM. 6 slots is aftermkt and usually plated bright zinc, OE was dark phosphate


All the OEM idler arm, pitman arm and tie rod nuts were 3 slotted As far as Im aware


PS, I think a lot of the OEM lower ball joint to backing plate nuts were 6 slot but dark phosphate plated

They are called castellated nuts

You can still buy the OEM nuts from AMK Fasteners https://www.amkproducts.com/bulk-fasteners-products/?Product_ID=11486

Gus

AMK offers 1/2", 9/16", and 5/8", but not 7/16".

Check Fastenal.

Factory used both.

That literature may show that.

But show me an original car with 6 slot nut ,,, other than what the I mentioned

I've found both styles on original cars.
Doug