There is synthetic enamel, and acrylic enamel, I would read the label to try to determine the type of paint John Deere is selling. The can of hardener should tell you which kind it will work with, or call NAPA for that info.

Many paints are designed for use without a catalyst. Adding a universal catalyst will give the paint more "toughness" than it would normally have.

Judging by the price of the John Deere product, do not expect miracles! You have to ask yourself why 99% of the automotive paint & body shops spend a tremendous amount on materials? It is not because they want to help our economy. :-) It is because the cheap stuff is not normally acceptable......not even close! As a general rule, if you use a good quality urethane paint system, it will last 10-20 years....instead of 5 years or less!