There are 3 cross members on your frame. One in the front, the middle,(bell housing) and one in the rear. Are you talking about the Bell housing cross member? They are all important other wise they would have not designed it that way. I have seen people take out the bell housing C. member out and that is way to much space with no bracing. Your frame will flex with the C. members. So imagine what it would do with out it. Hope that's the one u r talking about.
Jonesy