3.55 rears will take a lot away from your acceleration at highway speed. At highway speed it will do almost do nothing when you step on the gas. With a stock transmission, there is too big a gap to drop down a gear which will lead you wanting a close ratio 4 speed. This makes a nice cruiser. However, if you have faster gears, you will have less engine braking and you should consider upgrading the braking system. If you are going to be going faster, your steering needs to be in top shape. 3.55's are only a starting point. It can get to be a $3k or $4k deal. I personally don't care for anything less than a 270 GMC or better yet a 302 in front of 3.55 rears, but that adds to the tab also.
