I haven't used ECS windshields, but I have bought their date coded side glass for a 70 AAR and it was absolute junk. Ended up using it for target practice since they would not take it back. If you buy their glass and don't immediately install it and then find out it won't fit they will not let you return it, so don't buy it unless you are going to install it immediately upon arrival. I would never buy their glass again and would recommend no one else buy it either.