Buick LaSabre "clunk" sound

2001 automatic has developed a “clunk” up front when up-shifting. Had transmission serviced this past year (85,000 mi.). Transmission fluid level OK and clear. Navco guy says it might be engine mounts. Any ideas?

Open your hood and start your engine with your foot on the brake and shift from drive to reverse and back while observing your engine, If you can’t tell how much movement is too much, go to a used car lot and observe one that doesn’t clunk.

Tried this and couldn’t see movement. Thanks anyway.