Not sure if it's the same, but I noticed a shudder when I put the poly mount in my 06 Impala. I think it's being noticed when the DOD is transitioning between 4 cyl and 8 cyl. If I put the trans in D instead of OD, the DOD is canceled out and I don't feel the shudder.
2006 Imp SS all stock
1996 Z28 modded