Need some help have a 71 with a 340 and 727. in park while reving motor can feel vibration in floor boards. when driving and press on gas can feel vibration thru shifter and consol motor mounts have been replaced any ideas?

 

check/change your transmission crossmember mount first, if thats OK you might want to
move on to check the torqe converter to flex plate bolts, i have seen them come loose in the past
on small block Mopars.