Droid Engineer Archive

I'm fairly new as a DE so maybe this is a stupid question, but I just got expert droid blueprints and see the options for adv droid chasis for the surgical droid and repair droid. But the deed for those droids doesn't mention a slot for the chasis. Am I missing something here. what is the point of creating a droid chasis if there is nowhere to put it when creating the deed? Could someone please explain what is supposed to be done?

thanks.

You get the ADV model of droids at Master Blueprints. The ADV model uses the chassis.