In your case, you are SOL i suppose. You WILL have to compile for each version of RHEL AT LEAST - this is if you are lucky and all say RHEL 5 machines have the same libraries that you will need. And if you arent and you have different versions of libs you might have to compile multiple versions for the same OS.
By large, the hardware only counts in this case if you have to compile drivers for them, otherwise (drivers are available in the kernel) you will only have issues with supporting library versions (such as libc).
BTW a simple command is
To see the components.
PS If you have lots of work you should try to devise some plan to bring every machine to the same OS level.