Grinding/rattling sound on hard acceleration
 

I hear a grinding/rattling sound on hard acceleration particularly when cold from my 90 300 SE right front underside . Personally suspect engine or trans mount, but anybody has any other suggestions? I will be doing shocks and lowering of the suspension soon so I'm preparing to do a little poking around underside.
Thanks in advance

I had a similar problem on my 93 190E 2.6L, although it was a hard stop, not acceleration. It turned out to be engine mounts. The engine was almost touching the cross-member support on the left side. Worn out!