If you have a receiver with a C-Band input connection and a Ku-Band input connection, my guess is that it's an Analog receiver, but regardless, you will have to feed the C-Band with one cable from a C-Band lnb (or lnbf), and use a separate cable to feed the Ku-Band from a Ku-Band lnb (or lnbf).
most LNB's are usually good no matter how old they are. Unless lightning hit it or something it probably would still work. But you need 2 cables one for KU and one for C-band to go to an analog box. Digital you could use a Diseqc switch but the older LNB's only did one polarity at a time
If you have a Digital receiver, it won't have a seperate input between C-Band and Ku-Band, they both go into the same input. Then you could use switches and one cable to get both C-Band and Ku-Band to the receiver from the lnb (or lnbf).