Would the parts list from the equipment manufacturer tell? IE Deere will list the info.

Here is a link that might be useful: KAW info

been all over a bunch of kaw sites for parts none show the pto side of crank bolt fell out hate to buy from deere cost thing should be able to pick one up at hardware store just dont know what thread size is thanks tom

Measure the hole with an inside caliper.
It 'might' be metric. For length, use
a straight edge ruler.

Does Deere not list the size? I can't think that Deere's bolt price would be prohibitive if you had to go that way. It is an important bolt. And may I add sometimes a pain should you break one. Common crank bolt diameter would be either 7/16 -20 or M 10 -1.5. Best grade would be either an 8 or 10.9 . I would think that size of an engine wouldn't be a 3/8 -24. Use some blue loctite upon install.