Times 2 on this, don't guess. I know.The best way to measure is to get the rims and tires you want to run, put them where you want them to be in the wheelwells, and measure between the mounting surfaces. Anything else is just a guess.
What are you trying to accomplish....wider tire? With a mini tub you can usually compensate with a custom offset rim. It would be cheaper than shortening a rear end.car has be mini tubed. How much is taken out. I was thinking about taken a 1 1/2 to 2in off each side. Is that to much or not enough