1961-1968 International Travelall and Pickup Master Clutch Cylinder bolts. 3/8" diameter, 2 1/2" long with a 24 (fine) thread count.
These attach the master clutch cylinder to some firewall configurations. Use the photos below to confirm your needs. This kit has two pieces to complete your project. Note: Recommended, but not included are two 3/8 #8 flat washers. You should be able to get these at any hardware store.