Just went through all of this on my VX. Sizes are weird but can be remedied. Rge front speakers are 5", rear are 4", and tweets, well.... easy enough to figure out. Thing is, there is no 5" replacement. The best you can do it a 5 1/4". I went with 5 1/4" and they are perfect. Had to shave a little off the rear speaker mounts because of magnet size, but that wont hamper anything.

Good luck.