Washer fluid only Cap?

[67rsss350]

Okay you see them on eBay, what year did chevy start using the washer fluid only text bottle caps? I own a 33,000 original mile 66 corvette thats been in the family since 1973 and that cap is plain, but I did some work on a guys 69 vette that was pretty unmolested (that is until I put a new front end on it) and he had the Washer fluid only cap on his. I'm just making sure I got the right one for my 67 Camaro and I'm doing a restoration on a 69 Camaro for a guy and wasn't sure what he should have. His car had work done to it, but it looked like it had the old original crusty bottle and cap and it was plain. So two 69's both with different caps both looked very old and original but one was a corvette and one a camaro. Any ideas?