so i put a new transmission mount in my blazer cause the old on was showing wear. so i replaced it with autozones duralast. and ever since i replaced it i get a vibration when i accelerate. feel it on my floor board. so while i was driving i shifted my trans to N to see if any differance and i gave my truck some gas and still a vibration even in Nuetral. when you replace a trans mount do you have to give it time to break in or is it a defect part............

 

try a level on the drive shaft. if you had a dyno or rolling road, you could watch your shaft at low speeds to watch for latteral movment. i have the same problem kinda, but im pretty sure mines due to worn wheel hub bearings. to test, try to move the tops of your tiresin and out. listen for slight metal on metal contact... good luck