Replacing a mobile home water heater

[Swtgapeach69]

I have a 1996 mobile home with the original hot water heater in it. I need to replace it. It has 3 water lines on the upper side of it and a line at the bottom. The new one only has a place for 2 water lines on top. What is the 3rd one for in the old one and do I need it or need to do with it when I get the new one installed?

 

[GReynolds929]

The one with the lever is the safety relief valve. The flex next to it is the hot outlet. The flex at the bottom is the cold inlet.

 

[Swtgapeach69]

Thank you