Atwood to Suburban water heater.

[DonalMW]

Hello. I just bought a 2014 RESA. While testing the unit I noticed the Atwood GC6AA-10E water heater was bad. I pulled it out and purchased a used Suburban SW6DE and I'm trying to figure out the wiring connections to make. From the trailer there is Orange, brown, blue and red. (They connected to orange, white, green and blue on the Atwood). The Suburban only has 3 wires coming from it. Red, Blue and green.
Help please!!! We really want to camp for the first time in a couple of weeks before we pout it up for the winter.
I found the schematics for both heaters, but it'd very confusing for me......