The rear panels are hollow, with inner and outer layers and have a zipper on the inside that unzips so the stiffener panels (stiff plastic pieces) can be inserted in between the inner and outer layers of the soft top.
Here are a couple of pictures of what that zipper looks like. It's the one my finger is touching. My thumb is touching the rear window zipper.
The top you're looking at doesn't look like it has those zippers from what I can see.
Without the frame, it will be nearly impossible to tell a sunrider top from a standard top. Even then, I'd recommend speaking with the seller to get details on the top and ask specifically if it's one with the sunrider feature.
Given the challenges you have getting parts, you may want to see if you can get a used standard top cheap enough so you can see if it will work with your frame. If it does, great and if not, you know you'll have to buy the whole package, frame and top, new if you want to keep the sunrider function.
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