There is an active group of Darrin owners within the KFOCI who have worked out their own interchange information along with sources for various items.
Generally you will first need the Kaiser-Darrin Illustrated Parts List to identify all the part numbers. KFOCI HANDBOOK Version 5.0 (a perk that members get) not only has interchange info covering the change-over from Kaiser-Frazer series part numbers to Willys Motors parts numbers as well as the "big board" that chronicles all the running changes made to the cars (and there were a lot of them) during production. This version of the Handbook also has all the servicing information (including how to repair fiberglass) that the factory put out. There is no regular service manual, just the various Service bulletins under Kaiser-Frazer or Kaiser-Willys sequences.
