6x8 ranger replacement speakers

Any aftermarket coaxials that fit the mount will sound better than the originals did.  Don't worry about the sensitivity ratings, and actually listening to a pair at your local car audio dealer is the best way to decide on a model.  Otherwise, avoid the easy temptation to pick up brands found at your local everything-for-your-car shop (tucked between the wiper blades and floor jacks).

Notice I said coaxials...NOT 3-ways.  Speaker marketers often just add up supposed power ratings for each driver in an array, so don't place stock on power handling ratings on replacement coaxials.  Again, it is the listening that will tell you what you want to use.  I once had a pair of 50 WRMS Pioneers and a pair of 40 WRMS Pioneers which looked similar to each other and cones were made of the same material.  I liked the sound of the higher wattage-rated pair beter in that case.  But it could easily have been the other way around as the deck amp is only providing a couple of watts of power anyway.