i've had a weird vibration ever since i replaced my tranny. it comes on at about 2500rpm and slightly increases with rpm. ive been thinking that maybe something was unbalanced like the torque converter or maybe a cracked flywheel.but i got performance rebuilt parts from bowtie so i kinda doubt that's the culprit. i just remember that i switched to polyurethane engine and tranny mounts(energy suspension)when i installed the new tranny. are they stiff enough to produce these vibes? anyone else have poly mounts with similar problem? before the truck was glass smooth from idle to 5k.