I have lettered several revolvers.. the first being a 3" 66-4, primarily to get a production count (back when a letter cost $50). The precise production count of the "Ashland" 66-2s was given, along with a very vague number of all other 3" 66s combined. A letter is not worth the gamble if you want a production number.

On the other hand, I have lettered 2 revolvers solely for confirmation of being shipped to where I was told they were shipped to. Both were, and knowing that is well worth the money spent. And if they were not, it's still nice to know where they were sent to. One of the letters even included how many were sent in that shipment. I wasn't expecting that pleasant surprise.

My take...
Letter it if you need to know where it was shipped..
$100 gamble if you need to know how many were produced.