Rockola and external speakers

Hi
Does anyone know how external speakers can be connected to a rockola 464, regarding the terminal plate behind the chassis there are five terminals marked left and right channel and numbered 1 to 5, the existing internal speakers are connected to terminal 4. There are also the 70volt line terminals which i dont intend to use. I just wish to add two regular 8 ohm speakers, if i add them to the terminal plate do they need to be connected at lets say terminal 3 and do the existing internal speakers need to be moved to terminal 3 so that the output of the amp is not exceeded
seancalla