First of all four MOD AVO MK?, please see photo below, sorry about the poor quality.
I have been told that these are panclimatic models ?
7163.370
6259-15-667
13,104-3-72
3633,1267
Yes a few of the numbers them do seem odd
171716-C-266 conventional model 8, MOD
31883-C-255 model 8, civilian
68666-C-567 model 8, civilian
Finally I have two MOD model 40s which don't seem to have serial numbers, I've looked in all the usual places, battery compartment etc,
.
Julian