12/24 TM wiring question

[Fisher170f/s]

I have an older motor guide xp 6000. 12/24 with the switch on the foot pedal. I'm wanting to switch it to only 24v. My question is the foot pedal has a 3 wire plug(red, orange, black) and I purchased a 2 wire receptacle and plug. How can I wire this properly only run 24v? New TM batteries that will be in series with a red and black going to the receptacle. Pic below is my old plug I'm wanting to replace. Thanks for any help!

 

[Silvertip]

Measure the voltage between the black terminal and either the red or orange. 24 volt reading on the orange you use the orange and black wires. If the 24 reading happens on the red and black wires, use the red and black wires. Make sure you wire the two batteries permanently in series.