trailer hitch shaft/nut threads

[alfredr]

There isn't' one standard size. Best to take whatever of it you can to a hardware store and match it up.

[Donn]

phallic jokes...?? whatever...

Hm, small font there ...

[opus37]

Your choice to just test what you have is probably correct. From my experience, the threads/shaft on a ball come in two sizes. The light duty is about 3/4 inch and a fine thread. The heavy duty is about one inch and a coarser thread size. The hole in your hitch will tell you which one to properly fit it.

[roweenie]

IIRC, the UNC (Unified National Coarse) thread for a 3/4" bolt is 10 threads per inch.

That's the thread on my trailer hitch ball, FWIW - I assume there may be others.

[Dan Schultz]

...so riding mowers with worn-out/torn-up mowing decks have been converted to small (or not-so-small...in the case of the green one) "lawn tractors". ....

So.... is a mower a 4/4 and a tractor a 5/4? Do those come in silver?

[alfredr]

If you tap that hole for the trailer ball and then sometime remove the ball to use it with the box blade, if the blade is attached by dropping a pin through that hole, you will have a good chance of boogering up the threads. The more use it gets with a pin in that hole, the more likely and sooner the threads will get boogered.

But based on what is shown in the picture, I don't have any alternative to suggest.