4 speed to 4 speed od clutch chatter

I just find it odd how by just changing the gear box would create an issue. Everything is physically the same size other then the gears inside the case. For now I'm going to leave it alone.I had gotten a good deal on the cast od 4 speed and figured worth a shot. 1st to 2nd was a big rpm drop that my 6 pack didn't care for. For now I'll let it turn the rpm at highway speed

Duster with my original 4 speed is smooth as glass no matter rpm,hill, speed, burnout or anything. Going to leave it in the car.

As for the shake it was like nothing I have ever had before.I own over 10 muscle cars ranging from t56,t5, 833 and muncie so not new to driving standard.. but this was undriveable.