This is the extended life coolant we use. http://www.fleetguard.com/html/en/products/cooling/coolant/es_compleat/es_compleat.html

We also use WF2121 Coolant filters.

There is probably nothing wrong with your old coolant. I would keep it in a closed container somewhere and mark it well. Maybe one of these days you will run across someone with a leaky radiator that will be glad to get it.

How long is your 1950 going to last? I'm afraid you and I won't be around to find out.