I have been back to this one a few times and have a couple of possible theories. The military purchased lots of spare parts for watches (there are still lots of them out there floating around) If subject watch was repaired during the Viet Nam era by the military, it seems more likely that either the whole case was switched out, or the movement/dial were. It seems a fair assumption that if Bulova received an order for replacement movements, they would add a date stamp for the year of release to the govt.
If the case or case back was the repair issue, it would seem that the entire case would be replaced or the watch would be thrown in a parts drawer and a new one issued. Catastrophic case damage to a watch case would more than likely also include severe damage to the wearer. If the crystal was compromised, the damage would be the dial and movement (water). That seems more likely.
My thoughts are either this is a A17A with a replaced govt spare parts movement and dial - or it is a watch made from spare parts after the fact as we have seen a lot of those that originate is Asia. The source of the purchase would be a contributing factor. Was the watch from ebay or a vet's dresser drawer?
As Geoff stated, these are like Spaceviews. Highly desirable and prone to "reproduction" in this case, possibly from govt surplus parts.
It is also possible that somewhere in Viet Nam during the conflict that watches were in short supply, so the order was given to assemble as many watches as possible at a supply depot from spare parts to issue; We will never know.
My suggestions for ID of watch as presented would either be
1962 A17A with replaced dial and movement (most likely explanation) or 1962 Military Issue - no variant - also noting inconsistencies.