Logged on to good ole CougarBoard and I see a bunch of talk about logos and why the Stretch Y logo looks the way it does.

Back in the day BYU had a pretty basic block Y similar to the Y on Y Mountain. The basketball team even had it in a circle/oval on the basketball floor in the Smith Fieldhouse: https://pbs.twimg.com/media/E9PugObVoAU3VU2?format=jpg&name=medium
They put that oval Y on blue helmets in 1966 (Virgil Carter era). The story on campus goes that Coach Edwards met with a campus graphic designer, McRay Magleby, to update the helmet logo to debut in the 1978 Holiday Bowl. Here is a "helmet markings" brochure from the 60s-70s by a company called Angelus that shows various helmet decals, notice the section on oval letters: https://www.flickr.com/photos/65516705@N00/sets/72157626373347806/detail/

I'm not sure if this company came up with the G for the Packers, or if they based an entire alphabet off the G from the Packers. But they took the Y from Angelus, tweaked it a bit and changed the football shape around it to just an oval. In fact, there's a helmet on display on the second floor of the SAB by the football offices, and the oval around the Y is a football shape just like in this brochure. Look thru the pages and there are several logos that are still used today.