Most you have to cut the old connectors off and install new ones but has been pretty simple even for me.
My biggest problem is the kit I have has been set up for 69 to 75 I think and it comes with extra plugins for all the cars plus set up for all the extra like electronic speedometer, power windows and seats. Lots of extra wires to tuck up under the dash and all the wires are plenty long enough to do modifications.