anybody has the install procedure for the OEM hitch from toyota? I just got one today, but it does not come with any procedures. things that confueses me is that there are 4 loose plates, 2 seemed to fit on the side rails and the other 2 loose plates fits the top of the receiver, not sure how to install all these parts together. there is also another piece which looks like a cover for the bumper cutout, but my rear bumper does not have that cutout since it came out without the tow hitch package. please share your hitch install procedure and if you have pics of your install it would really help. thanks.