1992 Dodge Dakota 518 overdrive transmission

Question>>>Cant you just run a toggle switch on the computer controlled one to switch on the OD or is it more complicated than that. If it is an A500 with the capability to just use a switch to engage the OD I would be interested. If it is an A500 does anyone know if it will fit in a 70 Dart Without major surgery. I wouldnt mind a few blows to the tunnel with a sledgehammer but am not equipped to do major surgery. With an A500 is there major crossmember frigging??