With a 90 and an 83 in the driveway now I've had the fun experience of comparing them side by side. One big difference is in the sliding door handles/latch assemblies. The 90 needs only a slight turn to open while the 83 feels like it needs to be turned close to 45 degrees!

So here's the question: Is it possible to install the later style handle/latch assemblies into an earlier door?

john