Bolt size for OEM bumper

I recently acquired an OEM bumper for my 98. This is the bumper that covers the lower portion not the full brush guard. However, since this bumper was free it did not come with the needed hardware to attach it to the rodeo. Can anyone tell me the exact bolt size needed as well as the pitch. I already tried my luck at the hardware store and after a couple of strikes I gave up. I got tired of going back in and buying bolts that didn't fit. Now the last bolt I tried was a 10mm fine thread. Any :2cents: help is always appreciated.

Btt