I did the same thing for the rear end mounts on my Subaru Outback. jacked the rear end up and cut the rubber out of the mounts. Centered the bolts in the mounts and filled it in with the same Urethane you used. Let it cure for a week and its been good since, that was about a year ago. Totally worth the $6.99 VS dropping the rear end and $100 in mounts.