Hey there I am kind of new to the world of Model A's, my in-laws have multiple "doodlebugs" and many separate parts cars and recently they offered to give me a "AA" frame. Also I have access to most of their "A" parts, so I guess my question is what is the true difference between them? Are parts interchangeable? Will a model "A" body fit? I hope that this isn't to general of a question but any and all information on the subject is greatly needed and appreciated.