Old / New flashes and how not to damage a camera.

I have a Canon EOS 5 (A2 in some countries) and I am wondering if I can use my 600exrt ii speedlite on it.

I'm pretty sure you can't use an older EZ flash on a modern digital due to the power in the capacitor in the older flashes. I'm wondering if it's safe to use an EX on an older film Canon ?

Thanks