I know this has been covered before but everything I found on searches seemed to be dated material. Therefore, I thought I would share what I found today in my quest to find a CAT EC-1 rated antifreeze/coolant.
I am located in central NC so prices may be different in your area. I could only find a coolant meeting this spec at two stores.
CarQuest - Prestone ELC Heavy Duty - $21.99 per gallon
Napa/Walker Auto - Zerek Extreme HD Extended life - $14.79 per gallon (ZXED1 full strength)
(ZXEDRU1 = 50/50)
Both of these had CAT EC-1 on the jug.
Good luck and I hope this helps someone.