Thanks! I knew the info had to be there somewhere but I missed drawing #27 completely in regards to the spar.AN-3-16A and AN3-17A See drawing 27.
I found the spec'd lengths too long, requiring as much as four washers (one under the head and two to three under the nut).
However, perhaps that is intentional to ensure that the unthreaded shank goes through all spar and bulkhead materials.
Finn