A real head scratcher about vin tag numbers.

[Wizo]

Howdy all;A long time good friend of mine purchased this Saturday a 67 SWB with a big back window (bonus).I haven't seen it yet but from what he says sounds like he got a good deal.I have two real head scratchin questions about vin tags that i can't find anything on. The first 6 digits of his vin# are as such
C S 1 3 7 Z We can't find and have no clue what the #3 pertains to. everything I have looked up shows that,this number should be a 4, 5, or 6.
All the numbers on his frame, vin tag, title and SPID show a number three. Anybody have any clue or ideas why it is a number three or what it pertains to?
Next question; My truck is a 68 short step side that i got from my father in the early eighties.My father said it use to belong to the Oregon forestry service when he bought at an auction. underneath the line that is the normal vin # is another line of letters and numbers that are listed as such……B ID DDC 68 100
I haven't the foggiest idea what these mean. anybody out there have any ideas? I would really appreciate any help.thanks.