<snip>Could the rubber portion have a different density to compensate
> for the additional vibration of the diesel engine or is the mount
> physically different?
>

My diesel is smoother than my 2.1 WB. I know it doesn't answer your
question, but if there's a difference it's not that. Since I have both,
let me know and I'll look underneath to see that the differences might
be if no one knows the answer to your question... like that could
happen on this list.

Jim