Correct. I used a transmission jack with a big rubber pad placed on the trans pan. Any kind of stable support will do. When you get under there and look at that mount, it will be pretty obvious that the trans pan is where to put a support. It is plenty strong and there is not that much weight on the mount. Just use a wood or rubber block against the pan.

 

the motor is being supported by the 2 motor mounts.

since you're replacing just the trans mount, a carefully placed jack and 2x4 on a solid part of the trans will be enough.

 

This fixed my slight harmonic vibration at 45 and 70mph. Seems to shift alittle smoother/firmer also. One hour well spent.