I searched but could not find an aprox. cut off date for when the ribbed hoses became the standard. I know the GM logo hoses were on the early cars but when did they phase out? I have to replace my non original hoses anyway so I might as well get the right ones. Thanks for the help.
I'm not convinced the GM logo hoses were universally used on early production cars. The January '69 Hot Rod test Z/28, also seen in the April '69 PHR, does not have them. It was a very early car. Neither does the yellow JL-8 Z/28 seen in Car Life and Road Test August '69.
The only photo I know of that shows them is on page 120 of JM's 1969 Camaro book. Car was built November 1968.