The manual to my knowledge doesn't say much. It says "a special heat treated shear pin, part #300875-S8" is used. I never looked for that part and use regular grade 8 bolts. I think they are 5/16 and about 3" length, but any length long enough to go thru the parts would work. I rarely even take the time to use a nut. Just tap out the old broken one, align the holes, and tap in a new. I keep a handful in my tractor tool box. I can change one in 30 seconds, so it's no big deal to break one. I had an older ford plow with no trip protection. I broke it the first time I used it. Broke 4 grade 8 5/8" bolts in one loud pop. Repaired it and the next week broke the same bolts and bent the whole frame badly. I had to fabricate a new frame member and promptly sold it to someone with better soil (and a smaller tractor) than mine. I hope he had better luck with it than I did. I would not have one without trip,protection. The shear bolts work just fine. They are cheap and easy and effective. Just remember to carry a hammer, a punch or long bolt to use as a punch, and some spare bolts for shears. And as I said earlier, don't get in a hurry and go too fast and be ready to clutch in quickly to prevent shears. The more you plow a site, the less likely it will happen.
