C6 vacuum modulator hose

Does anyone know what size vacuum hose I need for my 73 C6 vacuum modulator? And is there a way to secure it? It looks like there is no room for a hose clamp.
Thanks
Dave

3/16 hose is what you use.No clamp is needed,just a snug fit will hold it on.If you want,you can put a small wire tie(zip tie) around the hose to serve as a clamp,but with a snug fit and vacuum on the hose,it shouldn't come off.