Among all the forums out there on coolant, no one seems to know the TRUTH. Not the International engineers, nor the Ford engineers. I am convinced that no one really knows regarding what kind of coolant is best for a diesel engine, specifically a 97 7.3 turbo, how much SCA to add and when, coolant capacities, color of coolant, etc, etc, etc...
I just did a coolant drain in my 97 7.3, the manual says the capacity is 32.75 qts. well, it took about 22-24 qts. which is what came out of it. I re-filled with plain old green walmart anti freeze and about 8 oz. of ford brand SCA.
There is a diesel truck repair shop down the road from me, and I stopped in and talked to one of the old-timer mechanics and he said. "how's the truck running"? I said, "great", no problems. Then he said, "then don't do nothing"! "If you must change out your coolant, then go to walmart and get the plain old green stuff and that's it". Just like we put in our 72 Nova's when we were 18 back in the 80's.
So that's what I did, but I did add about 8oz of SCA, like I mentioned.
Here is a bit of information for you, all your new engines with high emissions level components are running some kind of extended life coolant, mainly either gold, red, yellow etc. Starting in 2010 and later a newer coolant has been released that is nitrate free which is suppose to be good for 500,000 miles. My opinion is get some VC9 from Ford and get the engine hot or drive it for a few days, then drain the radiator and flush with a garden hose while running at high rpm's or remove the thermostat, then after 20 minutes or so drain again but this time drain the block as well to remove the iron system cleaner or (VC9) which can be corrosive!!. Grab some fleetrite extended life coolant from a local heavy truck shop and fill with that. My oil temp alone has dropped 20 degrees on my 2001 7.3. Hope this helps your 1972 Nova!! LOL
Looks like i got it right after all, I did a pretty good flush, and it looks like the walmart green AF is good for fords. I referred to the wrong manual, my system really does take about 24 qts. And,,,as many have suggested, I did put in 3 bottles of the ford brand SCA. Vehicle runs real chipper!! It ought to...she only has 80k miles!!! I just bought it a year ago, but now I KNOW it has good clean coolant and the right amount of SCA in it.