The easiest way to determine if your motor mounts are bad is to place the gear selecter in to "P" There should be little to no vibration. Next shift into "D", if the mounts have deteriorated this is where you'lle feel the vibrations. The reason for no vibrations in P has something to do with the engine applying torque to the transmission, you'lle have to dig into the archives to find out more.
As for the transmission mount, run throught the gears with your foot on the brake, if the shift selecter moves alot while the tranny gears up/down tranny mount needs replacing.
Hope this helps you to troubleshoot your problem.
Cheers for now