If you're wondering about whether parts and service for natural gas engines will be in your future, it might be useful to take a look at what engine and truck makers will be offering
4 Ways to Avoid Selling Counterfeit or Substandard Parts
One of your customers gets sued when his truck is involved in a fatal crash. Faulty brake parts are blamed. Before you know it, you get dragged into court because you sold it to him. You may say, "I didn't make it! I didn't know it wasn't safe!" The answer from the courts may well be, "You should have.