My answer is based on the parts book for the WW2 15cwt 4x4 C15A dated May 1945. The numbers could have been reassigned but it doesn't seem likely.
"378516 Shim, Front end shell mounting bolt (when stock depleted use 5822721)" - the thickness is not given.
3692225 - no reference found. Now for the guesswork - I think the numbers were assigned in sequence as the parts were developed, not relating to what the part did or where it fit on the truck (but I could be very wrong on this). Having said this, an assembly is likely to have close part numbers because it was designed as a unit but might include earlier part numbers if "stock" parts were used in the design. If this is right, the highest number in the parts book for the C15A is 5831817 so the design of your part must be before 1945. There are numbers in the 368xxxx range in my parts book, but no 369xxxx.
