No offense but you are out of your league on this one. The new control box uses 4 wire telephone TYPE cable called Communication cable. It is wired in reverse from a phone cable. This is a link to the manual for the Phone type tstat system which you have and it also has the single zone LCD 3 wire system listed. The single zone 3 wire would need a different upper control box from what you have. Doug
http://bryantrv.com/docs2/docs/operating/Installation_CCC2%20with%20separate%20control%20box_3312792.017.pdf