What are the thread size on the two bolts that secure the rops (roll cage) on a scat trak 1300c skid steer?
I can't help you BUT, if you can get one out, Lowe's has a thread gauge chart on the wall in the bolt isle at all their locations I've ever been to.
If you can find a parts diagram that shows the bolts it will probably list the thread size. Or if you can measure the inside of the female thread you can probably figure it out from the minor diameter (which is what you're measuring). It will probably be a Unified National Course thread.
You can sometimes identify bolt size by the size wrench required to fit the head.
Not to be too much of a worrier but: If you replace the bolts be sure they are of the same grade as the originals. 99.9% chance it will never be a problem. But if you replace them with some other grade of bolt and somewhere down the road someone rolls it over and gets hurt you could be liable.