There is no conversion kit to turn a Panel truck into a Suburban.
Here is a link to a post/thread/photos where someone asked the same question but for a 1947-54 Advance Design Suburban body style.
https://www.stovebolt.com/ubbthread...-54-panel-to-a-suburban.html#Post1346329

The entire rear body sides are different on a Suburban compared to a Panel truck rear body sides.

Two more links of post with photos of a Suburban with rear body skin removed.
https://www.stovebolt.com/ubbthread...rter-panel-with-skin-re.html#Post1346800
https://www.stovebolt.com/ubbthread...rter-panel-with-skin-re.html#Post1346956

You can cut holes in a Panel trucks rear panels to put in windows but looks kinda cheesy..
Better off looking for the real thing Suburban.