Cleaning glass

What is the best method to clean the 50+ year old glass from my Barracuda. I have the Windows out in preparation for paint and think its a good time. Working on vent Windows this coming week
I had BAD water spots on my glass....tried EVERYTHING....nothing worked...
Until I heard about using Barkeepers Friend (Google it...)
Worked like a charm!
(Like $2.00 at Walmart)

Jeff