I am fortunate (and thankful to my parents) to have been able to keep almost all my bicycles, frames and/or parts from then till now.
Of the bikes I do not have, my first bike, a blue heavily (emphasis on heavy) upgraded, AJ wheels, etc 74 stingray. A first gen all steel yellow mongoose (with custom made added brake bridge) and a first year issue all steel blue SE OM flyer.
Having said that, I have the frame and fork (along with most of the parts) that replaced the Mongoose. A Cycle Pro spoiler, purchased new likely mid 77. I had removed the original Cycle Pro Foiler stickers and replaced them with FMF in an attempt to fool people into thinking it was an FMF. It did not work, no one was fooled.
When I got serious about racing in 78, I embraced the frame as it was sold and reapplied Cycle Pro stickers. I raced it until the end of 79 when I switched to a first generation SE str-1 likely obtained in Dec 79 but that is another story.