i have a 2004 mach 1 with 47,000 miles and i just had a throw out bearing replaced at a well known mustang shop. everything was fine, i got out on the highway going about 70 and there was no vibration.. I downshifted to 3rd and gave her hell for no reason, was going about 95 when i started slowing down and once i got back down to around 65 there was a vibration that wont go away now. it seems to disssapear under 50 mph though. the faster i go the worse it gets. idk what could of happened, shook the driveshaft? or what but i drive about 80 miles round trip to work and back everyday and i dont want to drive with this vibration and mess something else up. any help would be great! ALSO, i was about a half bottle low on gear oil i noticed when i got home, idk if that could have anything to do with it.