We are going to purchase a 6509, how would I find out if the ws-x4306-gb1000base-x switching module in our 4506, will work in the 6509 ?
Oops.... I am sorry I interpreted your question wrong. Nops these modules are not inter-changable. This module will not work on 6509. Cat4500 modules are only supported on 4500 series chassis and they cannot be used on a 6500 chassis. Both the chassis have different line cards and they are supported only on their respective series of chassis.
So in nutshell, 4500 switch modules cannot be used in 6500 switches and 6500 modules cannot be used in 4500 series switches.
I am sorry again for the wrong interpretation of the question.
They all are compatible. The one way to check if the supported GBIC modules on both of the module on 4500 and 6500. They both support the same type of GBICs and if same GBICs are used at both the ends, they are compatible.
HTH,Please rate if it does.