Joerg - I see you've identified your '48 GMC in your signature line as a "Model 9434", a Canadian GM produced truck. For Shop Manuals to support your truck, you'll need both the 1947 Chevrolet and GMC Trucks Maintenance Manual, like this one
currently offered on ebay located in Nanoose Bay, British Columbia, Canada. Plus a 1948-50 Chevrolet and GMC Trucks Maintenance Manual Supplement to 1947 Manual
offered by Faxon Auto Literature in Riverside California.
The 1947 manual is the basic complete Maintenance Manual. The 1948-50 Supplement to the 1947 Manual covers only changes from the 1947 model year, so not a complete book by itself.
I actually own a set of both of these manuals in my personal "Stovebolt Library", so if you need some help or specific information for your '48 before you can acquire your own books, send me a PM and I'll be glad to try and capture and provide you with pictures of the manual sections you may need.
