I have old vinyl windows from '79 that currently have 24" long 5/8" diameter spiral balances. They have the red tip. Can I replace these with constant force balances?
As a manufacturer of all three types of window, balances, Caldwell are uniquely positioned to have insight into you question.
Does this look like your balance? Its Caldwells' EZ Lift series
Unfortunately, their constant force balances require a much different mechanism, so a new window would likely be needed.