I just bought my brother's 2008 RX350. I need to add a hitch and have been looking on Youtube for some information. It seems that some models are pre-wired with some type of two package that does not include the hitch itself. I do not have the original window sticker. Is there an easy way to determine if my model has the pre-wired system or do I have to disassemble the back in order to find out?