Off what engine was the C6 taken? If it's off a gas engine, it won't fit (different bellhousing patterns), and I'm not sure if there are bellhousing differences among the diesels.
Regardless, you're going to have all sorts of issues, as the E4OD is totally electronically controlled, and the C6 is totally vacuum controlled. The computer on your '94 isn't going to like it.
It would be a lot of aggravation for a lesser tranny.