Bunch of disorganized stuff from My Notes; some couuld be repeats
3m Window-Weld Super Fast Urethane thread where repairing the Engine Shock Mount is spoken of. polyurethane
http://www.peachparts.com/shopforum/diesel-discussion/314309-help-need-buy-engine-shock-mount-300sdl.html
Thread where Flexane was used
http://www.peachparts.com/shopforum/diesel-discussion/314569-cheap-engine-shock-mounts-fix.html
polyurethane caulk at Home Depot (~$8).
http://www.peachparts.com/shopforum/diesel-discussion/346705-filling-motor-mount.html
"BillGrissom I did so using black polyurethane caulk from Home Depot (search posts)"
http://www.peachparts.com/shopforum/vintage-mercedHomemade Polyurethane Engine Mount Bushings
http://www.peachparts.com/shopforum/general-information/324560-homemade-polyurethane-engine-mounts-bushings.html
When the owner found out the cost of new shock mounts, they elected to (emergency repair) try Polyurethane Construction Adhesive "Liquid Nails" – No. LN-950.
The whole thread from below
http://www.peachparts.com/shopforum/diesel-discussion/308791-380sl-diesel-conversion-project.html
Polyurethane filled motor mounts has shore hardness comparison chart
http://www.peachparts.com/shopforum/3061724-post317.html