I should have mentioned in my first post that my PowerPDA came with version 1. 8 initially installed as well. I have been using PowerPDA version 2. 0 for at least 6 months with no problem. If you have the 5. 9L, version 2. 0 should be no different to you than version 1. 8. The biggest differences are additions for the new 6. 7L engine and a new B model engine for motor homes. There may be some minor tweaks, but nothing that you should notice over version 1. 8.