I'm sure it's just a standard markup percentage. I can't see why you'd need to buy a Kubota one. With a bit of work, you can determine what kind of bolt it is and buy somewhere local.
I'd go with a Grade 2 to start.
Here you go from Grok.
Tractor shear bolts typically range from **Grade 2** to **Grade 5**, with **Grade 2** being the most common for many agricultural applications. The specific grade depends on the tractor, implement, and manufacturer’s specifications:
- **Grade 2**: Often used for shear bolts in lighter-duty equipment like mowers or rotary cutters. These bolts are designed to break under excessive load to protect the equipment. They have a tensile strength of around 74,000 psi and are softer, making them ideal for shearing.
- **Grade 5**: Used in heavier-duty applications or larger tractors where more strength is needed before shearing occurs. These have a tensile strength of about 120,000 psi and are harder, suitable for implements like plows or heavy tillers.
Some manufacturers may specify custom or proprietary shear bolts, but Grades 2 and 5 are standard in most cases. Always check the equipment manual or with the manufacturer for the exact grade, as using the wrong grade can lead to equipment damage or failure to shear properly. For example, a Grade 8 bolt (150,000 psi) is typically too strong and won’t shear as intended, risking damage to the tractor or implement.
If you’re replacing a shear bolt, match the diameter, length, and grade of the original bolt, and ensure it’s rated for the torque load of your specific equipment. You can usually find this information in the manual or by contacting the dealer.