Just went out and measured mine it's a little over 5" but you should be fine with whatever you have if your other measurements are good. The measurement your looking for really doesn't matter and has to many variables to make a decision based on it. But sounds like your pretty close to where mine is mounted.
Ok great thanks. I think i will stick with my measurements seems to be fine. This is the one step that i wanted to make sure was as close to perfect as possible. Once its on i can turnn back. Thanks for your help brett much appreciated!