I suggest that as an alternative you focus on installing good speakers in your 4 doors with external power amplification, and you won't even notice any need for those odd-sized speakers in the rear. I did this for both my 1997 Yukon (RIP) and my 07 Yukon, and I've long forgotten that those rear speakers ever existed.
If you are certain that you need those rear speakers, Crutchfield used to sell, and maybe still do, a retro line of 4x10 2-way speakers with two tweeters, and they sounded decent at a very reasonable price.