M38A1 valve cover studs

[mcscoggins]

I have a 1964 Kaiser-Jeep M38A1, USMC model. I broke one of the valve cover studs and am having difficulty finding a replacement or matching my stud to the specs in the 1956-era ORD 9 SNL G-758. The manual gives this spec: STUD, hex, spec, S, 5/16-24NF-3 (1/2) 5/16-24NF-3 (13/32) x 2. However, when I put a 5/16-24NF die on the stud, the die is a fraction too small and actually cuts into the threads. Do the late model M38A1 engines have a different size stud? If so, what is it, and does anyone know a source?

Thanks for any help!

MCS