Rear Slider Fit Question

[tristan]

I had hoped to upgrade to a rear sliding window on my 1971 during the course of its restoration. I found one with tinted glass on EBay and had it refurbished and installed.

Although the window looks fine on the inside of the cab, it is not fitting flush with the gasket or back surface of the cab on the outside. I have only seen pictures of them looking straight on so I don't know if that was normal. What say you? I still have the original Soft Ray non-slider, gasket and trim if I have to revert. I am wondering if the sliders had a different, thicker gasket, or if I got sold one that was for some other model.