Third-party auto repair manuals, such as Haynes and Chilton, are typically good sources for finding timing belt and timing chain routing diagrams. Both companies have been in business for more than 50 years and have repair manuals for most makes, models and years of commercial vehicles.
Haynes and Chilton auto repair manuals are both available in a variety of formats, including hardcover, softcover, CD, DVD and online versions. The manuals also contain step-by-step procedures for diagnostics and the adjustment, tension and replacement of timing belts and chains. Both Haynes and Chilton charge for their repair manuals, but both sites also offer subscriptions.