RE: Replacment 72mh red flag
72 MHz radios are still alive and kicking, the red ribbons that came with those systems were very useful to check light and strong winds conditions, I use mine on my 72 MHz synthesized system, and also a lot of people at our field (with 72 MHz systems) use them. If you haven't the original one, do not worry, and as suggested use any red ribbon just to check the wind conditions.
Best Regards.