How to check motor mounts?

What's the best way to test engine mounts?

Mine LOOK okay to me. I don't see any disintegrated rubber, cracks, or tears.

However, when I start the Jeep sometimes it sounds like the engine is moving around just a little. My transfer case shifter sometimes vibrates at idle, and sometimes when coming to a stop or starting from a stop, I get a clunk. I used to think this clunk was slop in the transfer case chain, but now I'm not so sure.

It looks a lot easier to get to the mounts, particularly the drivers side since I have the manifolds/ head off. I may just pull the mounts for inspection/ make sure all bolts are good, but looking for some input before I go tearing more of the Jeep apart.

Chock the wheels and put it in drive and have someone give it gas while standing on the brakes and you watch the motor. Then do same in reverse. You will be able to see how much movement the engine has.

Don't do it for prolonged period of time as you can heat up a transmission pretty fast if you do it too much.

Check the trans mount, also

new trans mount is like $18 on ebay...i went to change mine and snapped off transfer case support bar bolts :/ ho hum. held in by 2 bolts now

I would check the transmission mount like 93gc40 said. I had a bad trans mount and it allowed the my clutch fan to make contact with the radiator.