I saw this new book advertised. Not sure if anyone is selling in USA yet.  Looks interesting:

http://www.crowoodpress.co.uk/2004/book_details.asp?ISBN=1+86126+763+0

VW Camper - The Inside Story 
Author: Eccles  

A guide to the various camping conversions and interior layouts used for VW Campers 1951-2005

This book documents and celebrates the many different camping conversions built on the Volkswagen Transporter and Microbus base across five decades.

Until the advent of the new T5 generation in 2004, Volkswagen never made a factory-fitted camper, preferring to approve conversions carried out by firms such as Westfalia, Devon, Dormobile, Sundial and Danbury. However, many other different companies offered conversions on the VW base and the models produced by over forty different converters are described and pictured here.

Michael
My VW web page: http://www.velocity.net/~vickrail/moshevw.htm