Hey there
@Squishynappy nice to meet you. I myself am somewhat a self-proclaimed vintage Pampers expert (LOL). I have been collecting vintage diapers for coming up on 25 years now. I have been addicted to the 70s era fanfold Pampers since I wore them as a baby myself (back in the late 60s and early 70s and then again as a bed-wetting teen in the mid 80s). I have a growing gallery collection of almost exclusively Pampers, but there are various international brands featured, as well as some adult diapers and some vinyl/plastic pants. Mainly, my fetish is driven by vintage diapers and plastic pants that feature a type of super supple plastic that is often called "diamond-embossed," "rubberized," or "taffeta textured." To the untrained eye the textured on the plastic simply looks "dimply" or like "little bumps," but if you look carefully those little bumps are usually diamond-shaped (thus the name).
Can you take a closeup photo of the odd-looking pleated diapers you mentioned? I should be able to identify the make, the year, and even the size if you have measurements. From there I could probably identify the box or bag they came in (since I have so many photos to browse through).
For reference of what I am talking about, here are some closeups of vintage 70s era pleated plastic Pampers diapers featuring the (now extinct but still famous) diamond embossing:
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