I have a 2007 sport v8 2 wheel drive. I would like to change out the stock suspension with the fj cruiser set up. Found a set of 2007 4wd fj cruiser front springs. That's all he had for sale. I then found a set of rear springs from a 2007 2wd drive fj cruiser. Is there any difference from the 2wd springs verse the 4wd springs. I want the my ride to sit level and have a good ride. I also tow a 6000 lbs boat so I need to keep the back-end from sagging. I plan on putting on the Bilstein 5100 shocks.Will the 2wd springs work or I need to go with 4 wd springs all the way around. Do I need to put a spacer on the front also. Thanks for any information.