Browning offers letters now for @ $40 USD
Browning offers history letters for @$40 USD
Check 1966 gun catalogs
Browning.com has a sn fucntion under customer service.
With no other data provided, 100-10000 USD
Browning.com has sn data under customer service.
Go to Browning.com and look for serial numbers under customer service
You will need to conatact Browning and order a letter from them
100-10000 USD or so depending on specifics