It looks like the newer units will not fit your existing outlets based on my observations in servicing many of them. You might try the Suburban website for dimensional drawings, or call their tech line for more info.
New units can mount either from the inside or outside of the rig. You might be OK if you get an exterior mounting model and get a brushed stainless or aluminum cover for it. It would blend right in to your exterior of the trailer, and you would have a perfectly aligned cover too.