Hi there,
Thought you might want to see these photo's, both came from Footnote. They show standard P-51 and P-38 drop tanks that have been filled with napalm, both show the fuses about to be fitted. Although the info. on the P-38 photo states it is a M-14 igniter, it may be a M-15.
You can google 'TM3-400' to find the tech manual showing diagrams of these, although it's the 1957 version.
Regards,
Michael