Are you talking lug nuts or the bolts with the cotter pin that holds the drums on? The lug nuts are 1/2-20, front and rear, 5 per wheel. This is from the AMA (Automobile Manufacturer's Association) Consolidated Specification Questionnaire, page 15. The 1951 Kaiser Illustrated Parts List does not list the particulars. Don't you have at least a couple you can also use for physical comparison?