78 Dodge Truck Heater Core

[TeamSpatula]

Hi. The heater core on my mom's 1978 Dodge truck is leaking, so I was going to replace it. However, it's not covered in the manual I have. It looks like if I take apart the plastic housing inside the cab, on the passenger's side, that I can get to it from there. Has anyone out there done this? Is it pretty straightforward, or are there any tips or tricks I should know. I'd like to have at least an idea of what I'm getting into before I start taking things apart.
Thanks,