Finished changing my transmission this morning in my 2004 Trailblazer 4wd. Seems to be running good, no problems shifting or anything, but ever since i took it off the rack there is a big vibration sound. Sounds like its right under the shifter. At first it seemed like it was only when i was in reverse, after driving for a while it does it in drive also. Doesnt seem like a transmission problem, but funny how it never happened until changing it. Any input would be appreciated.