Most speaker manufacturers don't build their own drivers. That is done by the OEM (original equipment manufacturer). The units can be stock if the manufacturer is only buying a few drivers, a modification of a stock driver (ie: i have some PSB labeled Vifa P17s that have different specs from ones you can buy), a new driver based on available parts (ie Shiva -- OEM is Eminence), or a completely proprietry (ie Jordan -- Vifa is now the OEM).
Do you know the make and model number of the speaker the driver came out of?
If you do, then you can look up the speaker-or Email the manufacturer-and find out how big a box, (and what type-ported or closed), the speaker was in. This will tell you a lot about how the speaker will work in any box you plan to build.