Check out these nuts. (Problem solved)

If you guys want some good advice...skip all that crap from the factory and go buy an ARP oil pan stud kit for a Pontiac...and use those for your intake exhaust studs/nuts. They have bulb ends so that never strip when the manifolds go on n off and WAY STRONGER and fine thread for excellent clamping. Unless you're doing a restoration for conquerors judging you're wasting your time trying to find this old crap.