2000 Dodge Dakota Vibration from Dash when Air Fans turned

Hello,
Recently - my truck begain making a horrible noise when the vents/ac/heat is turned on - the entire dash shakes. I believe either the clean air filter or insullation have dropped onto the blower - rattling when hit with the blower. How do I get to it on my Dodge Dakota - I've yet to find anything online showing how to gain access to the blower area.

Thanks,

Jon Seilkop