we were pricing the replacement of the main tube and awning (21 feet) for our 1972 International. We received a quote (Zip Dee) o/a $1750 plus $200 for shipping from a very reputable dealer. Installation would cost a few hours, but be done correctly. We've replaced all of the roadside awnings with Zip Dee and rear bath one and are very pleased with the products. We lost these due to high winds in Texas 10 years ago and finally saved enough to do them right. The installations were done perfectly.
Its funny you mention this as we have encountered a few folks RVing this summer who have attempted to replace their own awnings to save a few bucks. Their shipped awnings either sit on the side of the SOB RV or are hung by other means and you can see the savings they achieved are not viewed with a smile, but they have their awnings. I always hear we should of let the technicians do it. But there are some folks out there that are very good at this. I met one that did a great job installing the awning. But his dissatisfaction is due to the wrong shade of color being ordered or shipped (they are still trying to figure that out after $1675.00), and it being a no returnable due to being a special order , as he states, it almost compliments the rest of the other four awnings on their SOB RV.
As mentioned above by wahoonc, find out your brand as the arms and everything else needs to fit and I've had both carefree side and zip dee main awnings, so they could be different, but with the same material. Back then, I guess they could do that.