Has anyone else had this problem?

About 3 days ago I was driving my 87 300SDL and I heard a howling sound. I could feel the vibration in the accelerator. It quit for a day and is now back, but only when I am going between 25 and 40, accelerating, and I am drifting (slight turn) to the right. It is coming from the front of the car... maybe drivers side, but I can't tell for sure. Kind of a WWWWHHHHHHRRRRRRRRRRRRRRRR sound high pitched.

I know I need to replace my tranny mount and motor mounts. MB guy said they are in need of replacing. Could this cause it? Brakes are new, tie rods new, steering shock new.
Any ideas
Thanks

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Rick
Safety Harbor, FL
1987 300SDL 280K