As far as chassis it looks like the only thing that changed was the rear. It has a slightly longer wheelbase but they're not boasting added cab room or anything.
It looks like the wheelbase is 73" for both.
Just from the pictures the rear of the frame is diffrent where the bed attaches.
But it looks like the intake and exhaust have been reworked.
It's probably easy to do just moving tabs and brackets around but keeping the frame pipes the same.
Also, it looks like a lot of the accessories cross over to the p520 (p500 accessories are not up on the web yet)
This suggests there is a lot of common parts.
Have to wonder if the new style doors will fit my p500 (probably don't fit my riding style).
And I like the look of the nerf bars but I bet they don't keep the 50" width.
Forcing tires threw a 50" gate is one thing, hard parts are not going to squeeze threw as easily.