M103 + W126 cars eat up motor mounts, regardless of brand. Plus the damned exhaust downpipes are routed a bit too close to either that caster rod bracket support or idler bushing. I fixed the support brace by putting a dimple in it, now the pipe sits on the idler bushing.
I am to the point where I am going to make some metal shims to gain the needed 1/2" of rough clearance needed to stop this NVH. My mounts are not fully collapsed, just sagged a bit. Not interested in spending $200 for OEMs currently.
Permanent solution is to reroute that downpipe, I am nearly to that point.
Aftermarket trans mounts work fine on these W126 at least.