They are "clutch head" screws. You can buy a full set of screw drivers for these through any of the old chevy parts places for around $16.00, i.e. Chevy Duty, Jim Carter's, Chev's of the 40's. Or I bought a cheap set of tools at Checkers around $19.99 that had three different sizes of these included in with the bit-driver selection. Lastly, if none of those suit your desires, check your local RV store. They are still using these types of fasteners on alot of the newer RV's being made today.
