This is from Valspar which makes the the ironguard paint:
"This is an alkyd enamel. Recommend you use CNH thinner (which is medium temperature range enamel thinner). You may use hardener with the product (CNH dealers carry REN3001) Paint to hardener to thinner ratio is 8:1:1"
In general you can go down in quality but not up, so acrylic enamel reducer should work with alkyd enamel. I am not sure about the hardener but I would think any alkyd or acrylic enamel hardener would work. When in doubt, go with the manufacture's recommendations.
Reducers are more than just thinners, reducers may contain acetone but acetone only as a reducer may not give great results depending on the temp and humidity. There is a reason why reducers are made they whay they are and not from pure acetone.