Very hard to find any of these at all on the market. I believe the mint only made 1000 of them. Numista rarity scale has it at a 97 out of 100. This one displays a strike thru string or thread on the obverse.
Interesting example of the Diplomatic Courier Service (DCS) medal, thanks for sharing.
The silver DCS medal was also available in a plastic display case and in a philatelic-numismatic cover (PNC). Shown below is the PNC; I'll try to dig out the one I have in the case and present it here later.
The medal was also struck in bronze and gold-plated bronze.
Notice on the PNC that the silver version of the medal was released in 1971 - three years after the anniversary date shown on the medal. The small versions of the Mint's List medal for the DCS were not issued in 1968.
Collecting history one coin or medal at a time! (c) commems. All rights reserved.