When I replaced my clutch (120K miles), the guy from the shop tried to point out that my engine mount (left rubber) was bad. What he did was, had someone led go the clutch to make the engine vibrated and died. At the same time, you would check the rubbers outside if it would absorb the vibrations of the engine. I saw the left mount was bad. Anyway, he said it would cost $200 to replace it. I told him that I did not feel any wrong while driving, so I did not replace it.
Now, the pickup has 270K miles and doesn't feel like any abnormal vibrations from the rubber mounts.
I guess you can jack the engine up from bottom to get the old one out. Let us know what the outcome is. Good luck.