[MRCG] Help identify crystal container box

[Jay Coward via MRCG]

Group. 
 I just acquired a "cute" crystal case on the ePay. It is a narrow, long case, hinged at one end and has a hasp/snap closure at the other end just like what is used on (many) Mil test gear covers. It holds 10  crystals with FT-243/ CR-8 B/U pin spacing. It has small flanges at each end with 2 holes each (#4?) for mounting to something .
 The top cover has the following: 
CRYSTAL KIT CONTAINER FOR TRANSMITTERS
 T-363/ARC                                    T-365/ARC
 T-364/ARC                                    T-366/ARC

No other nameplate, absolutely nothing and no extra holes where a nomenclature plate could be mounted.

 Mystery? Yes or No

Jay KE6PPF