Usually it's just the front bushing. If you get under there check out the back two and see if they're bad as well.
I just had mine put in from revshift and man what a difference! Also changed out my motor mounts as my car was vibrating a little to much. Here is the revshift link.
Yes I checked that before and only front one is damaged, the rear two looks ok but I prefere ask, just in case to avoid double labour.
Mine problem is similar when shift from R to D or from N to D the diff is jumping in broken mount. I can easily lift the diff by hand.
Also when downshift I feel the knock. Firstly I was thinking there is something wrong with tranny but when I lock the gear in manual mode and I pressed and relased gas pedal few times it's still knocking.
Differential front mount definitely need to be replaced.
revshift does not provide a special tool(at least I don't think so) for the metal sleeve, but yes you will need one. I tried BEATING it out myself but failed miserably!! I had to put everything back together and take it to a mechanic.