the pitiful FR manual that comes with all their RVs, is useless, generic and will not show/tell you where they are at.
since you have an older model, you will need someone who has the same year/model or at least the same year, to know specifically.
mine are under the sofa but FR changes locations often. my same model a couple of years later, had changed from blue/red lines to translucent lines and also changed the drain valve locations.
look underneath for drain hose ends and then go inside and look directly above those.