That actually might also indicate the transmission mount, if it rocked downward at the back. You need to think about how the force is being transferred from the engine.
The engine only rotates clockwise (as you are looking at it from the front) so in drive, everything rotates the same way. The force (since it is being stopped at the wheels) will actually shift the engine counter-clockwise toward the passenger side. That side would dip.
In reverse, the opposite is true - the force outbound from the transmission wants to rotate the driveshaft counter-clockwise, and since it again is being stopped at the wheels - the engine dips on the driver's side.
Sounds like you have found the problem tho, be careful when changing them! If you don't have access to a shop crane / engine hoist, (I didn't) a 2x4 as padding under the very front of the oil pan with a floor jack can work wonders.
If I was doing it again, I'd certainly go the shop crane way. Much safer, now that I think about it. Just remove the fan and shroud from the radiator no matter which way you do it, and you will have plenty of room to flex the engine... Until the transmission pushes into the firewall.
