need help id'ing a car

hi im a diver and we found a car awhile back in the river its been there a long time and weve been trying to figure out what the car is. its buried under a buncha rocks so we cant see all of it and have been slowly moving rocks away from it. today we were able to get a look at the engine and the radio and the vehicle no. plate the radio says its a plymouth and they engine looks like a v6 the intake manifold has the numbers 1859228 on it and 3x11x6c and then on the drivers side inside the door hinge we found a plate that said vehicle no. 3205119387 i figured it was a vin number but searched it and couldnt find anything. so if anyone has some ideas or advice to what it is thatd would be awesome thanks.