Bouncing In Driveline At 3000 Rpms

[toofun]

Well this is what I was able to find out so far, barring aside the info you have already relayed to me.

The cross member I am using is a forte crossmember as seen here http://www.5speedtransmissions.com/5spcrossmember.html. The first hole lines up but the second hole does not, so the crossmember is only being held on with one nut and bolt on both sides. I plan on drilling another bolthole for both sides in place tonight. But even with the setup the way it is I noticed that if I push up on the crossmember it will flex a little bit up and down in the middle. Almost the same distance as what I see in the car. I dont know if it is because their is only one bolt on each side, if it is because the driveshaft is two inches too short, if it is because this crossmember has too much give in it or if it is a combination of all three. Is it suppose to have any give to it at all?? Has anyone else used this crossmember? ANY OPINIONS would be appreciated.