Let me apologize in advance for my ignorance on the subject, I may not know the correct terms but please bare with me. I'm putting a Tremec 5 speed in my car... The slip yoke that comes with the tranny is a C6 Ford slip yoke. My question to you, will the C6 slip yoke bolt up with my driveshaft and u-joint? (Assuming that the driveshaft is the right length of course) Are universal joints really that universal? If not does anyone have any suggestions on how to go about forcing the two to work with each other. Thanks so much -Adam

It is not likely to fit. They are not that universal. Forcing it will assure a failure.
You must either get the correct yoke, which may not be offered. Check with the trans supplier. Or you could have the drive shaft modified. This is the more likely answer. There are several companies that will rebuild, modify, and ballance your drive shaft. They can make it the correct length while they are at it.
I can have this done locally in the Akron Oh area, so check around. You may have someone close, or you may need to send it somewhere.