I photographed these M31 Honest John examples at the Fort Lewis Military Museum and Duxford.
M31 Honest John
Previously identified as M50, but 2026 visit had signage confirming M31 (longer and taller fins).
Fort Lewis 2015
Fort Lewis 2026
M31 Honest John mounted on M386 International Harvester TEL
Honest John missile displayed mounted on the M386 Launch Vehicle in the Land Warfare Hall of the Imperial War Museum