I'd measure it myself but it's on my property 20 miles outside of town. I have one stretched bolt on my 72" side discharge deck. When I first noticed it I measured it quick and thought it was a 5/8 x 2 1/2" long bolt. I bought a standard course thread bolt and found it wouldn't fit. So my question is it 5/8" fine thread, a M16-1.5 x60mm long or a M16-2 x 60mm long? Hate to by one of each cause the hardware store charges $2.39 each.