I have an 81 Camaro with a 383 making 430 hp/466 ft/lbs of torque at the fly wheel. I have a stock suspension and 373 ring and pinion gears. I know a posi would help and I plan on getting one, but I don't think it will completely fix my problem. Also, I have 11 inch wide tires on the back.

 

A posi/limited slip will help greatly. Nothing is going to completely fix your traction problem if you go standing on the gas pedal from a stop. The type of tires you have makes a difference too. I used to have the old school N50 tires. They were a hard rubber compound, and even with a 12" wide tread they would still break free very easily. I put on the Firestone Firehawk 295/50/15's. And even though the tread is only 10" wide, they stick a lot better. How you drive the car is another factor. I normally get the car rolling just a little, then punch it and she hooks. You say you have stock suspension. Add some traction control...traction bars, etc. That will also make a difference helping to prevent the tires from breaking free as easily.

 

Adding an extra leaf to the spring will also stiffen it up and also raise the back a little adding more tire space.

 

Ditto on everything they said! Posi, traction bars, the right tires, (and tire pressure) plus throttle control. I don't have any real traction problems unless I want to have them. Sometimes it's fun to light 'em up a bit, but I can avoid it to the point of nearly liftting the front tires if I want to.