I have posted a video on you tube on the installation of a G6a-8E hot water heater in my Safari. The installation took about 3 hours from start to finishing the clean up.
The steps to be careful of are:
1. Turn off the water and Propane.
2. Depressurize the tank.
3. Drain the tank.
4. Put a towel under the water lines when cutting the water lines loose.
5. Careful with that gas line..do not crimp it when loosening or tightening.
6. Soap test the gas fitting when it is reconnected.
7. Use plenty of plumbers tape... it is cheap insurance.
8. Have someone else look at the installation before you fill the tank.
9. Go back in an hour and double check everything one more time.
Here is the link. Hot Water Heater Installation.mp4 - YouTube