I've heard everyone talking about getting lightweight flywheels to improve the acceleration and letting the engine rev after, what about a lightweight driveshaft? Will that be a good mod to boost acceleration? Anyone know anybody that makes them?
I hear a clunk when I shift into first and I am suspecting the driveshaft is going to go, just thought about the lightweight driveshaft.

 

Yes, a lightweight propeller shaft would help your car's performance slightly, but your problem sounds more like shot transmission mounts and/or suspension bushings.