I've done it. A 99 4.0 is a little quirky because not all the factory components are available. The plus is you get a better compressor. The minus is the mounting gets a little creative. But its 100% bolt on. And nice to get everything in 1 box. I use Nylog on all my o rings which is not included. If you don't have a vacuum pump and a refrigerant scale, pay a shop to charge it for you. It needs to be exact!