I have a c4 transmission and these lines come from it to the back of the engine.I am using a cobra intake and i have one port to connect the fuel pressure and one that's open.do i connect one of these to the intake and where does the other hose go?or do i run a t and connect them both to it?

That would be a 1973 or 1974 c4. The dual vacuum lines were used with the dual port modulator when the engine had EGR. Couple things you could do. You can replace the modulator with a single port green stripe one. Or you could use the one you have now and just block the forward port on the modulator and run manifold vacuum to the rear port only.

Don't forget to get your going to need a big vacuum port for the PCV valve.