Vibration shows up at the same rpm while going down the road. No, the car isn't up on jack stands when tested. It vibrates at rest on all four wheels. If you are going up a hill and can keep the engine at a constant 3000 rpm, it will begin to pulsate. Increase the rpm to 4000 and it diminishes. Same at rest. I tried loosening the motor mount bolts to see if that might make a difference, but no change. Haven't tried anything with the tranni mount. I do have a Gear Vendors (OD). It does seem like the poly mounts are almost like solid mounts. Any vibration at idle (slightly rough due to the cam) is transferred to movement of the body. They were extremely tight in the K-frame. I used the original motor mounts, burned out the rubber, and inserted the poly inserts. I still would like to throw in another 727 just to rule it out. I say that because back in the 80's, when I first put the 727 in with the 340 and 410 gears, I had some vibration issues going down the road at about the same speed. I thought it was a drivetrain issue because it wasn't really noticeable at rest (rubber mounts), and my driveshaft was shortened without balancing. I even tried a counterweight on the tail housing. I finally put 323's back in and it was better at cruising speeds. This brings me back to the transmission since it is the only original thing left. That was a long time ago, so my memory of how it was is a little vague, but it did start after I installed that transmission.
