Whichever one it is, don't do it manually just let the windows updates download it and it should download the correct one. Or you could manually try installing either one or both, it wont do any damage as it will only allow yiu to install one or the other.
Whether it is X38 or X48, or even X58, all have the same chipset drivers installation file.
It will only install the device ids for corresponding chipset.
Anyway, if you want you can post a screenshot of the device manager showing the system devices in expanded view.
Is this a desktop or laptop?
By the way, you can always run this utility to install the unknown devices:
All the best,