I get a clunck when I shift into reverse from park when the car is cold, if the car warms up it doesn't do it ? Any help greatly appreciated.

What is the idle RPM when shifting into rev when cold? High rpm can cause this.

Cold trans fluid is thick...it can also cause a firm/harsh engagement when cold. 

Also, check your u-joints, and the front diff mount, as any of those can create clunks or other noises/feels.

Thanks for the response, I think its gotta just be cold fluid. I adjusted the rpms at idle to about 1100, this is after it drops down from the initial high idle of about 1400. While driving after its warm I idle about 700 and it shifts into R fine. Also and this might sound crazy but if the car sits out in the sun for a couple hours it also shifts into R fine after startup. I changed all u joints and the differential mount as well. Somebody also said perhaps there is a shift kit in the car but I'm not sure how to verify that.

1100 rpms is a bit high....you have to expect a harsh engagement at that rpm, hot OR cold. Let 'er warm up a bit more to get the idle speed down before taking off...or just live with the firm engagement. Fluid viscosity at that rpm is moot. 👍

Joel thanks for your help and I agree, lately I have been warming up the car a bit more and the shift engagement is pretty mild. I just wanted to make sure I didn't have a problem developing. Thanks again !

😃

As far a shift kits, they typically don't create harsh engagements, depending on how the unit was built. If the 1-2 and 2-3 shifts are always firm, but on time, then it's possible someone has done something to the unit such as a shift kit. Hard to say unless you dig into the trans. The calibration on Corvette transmissions were a little more aggressive than for Ma's Impalla, so they shift a little better to start with.