Always best to use an aluminum backing plate. Only needs to be slightly bigger than the diameter of your Ram mount base. I used a 4″x4″ plate to mount a D-111-U (3.65″ base, 2.5″ ball). Make sure the backer will fit under the dash in the area where the base will be located, position the base and mark and drill the holes. Re-install the backer and mark the pre-drilled holes. Take a look at the Transducer Shield and Saver mounting base. Comes with SS hardware and makes routing your wires easy. I used a little 3M 5200 behind the backer and the base. Always best to use an aluminum backing plate. Only needs to be slightly bigger than the diameter of your Ram mount base. I used a 4″x4″ plate to mount a D-111-U (3.65″ base, 2.5″ ball). Make sure the backer will fit under the dash in the area where the base will be located, position the base and mark and drill the holes. Re-install the backer and mark the pre-drilled holes. Take a look at the Transducer Shield and Saver mounting base.Comes with SS hardware and makes routing your wires easy. I used a little 3M 5200 behind the backer and the base.
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