Alex, thank you very much for the links! Very usefull.
For the distributor cap: M37 production started in 1951, also canadian M37CDNs where produced. The M37 used the same straight6 engine as it's WW2 predesessors.
The Dodge APT was produced in 1945 in 2 batches (of around 5000 each) I found out that the APT i have is from the second batch and these where, unlike the first batch, wadeproofed.
We never had M37 in the family so my only guess is that the norwegian army, my APT was used in, did an "upgrade" from the original wadeproof (round) distributor to the M37 wadeproof distributor. But...this one is 24V
Here is a photo i found on the net.