The following are a collection of publications that may be able to provide that elusive piece of information.

Publications

Jampot
This is the monthly 47 page magazine published by the AJS & Matchless Owners Club (AJS & MOC). Each edition includes, articles from members, News and Events, Wots On?, Technical Topics, Around the Sections (local club news), Members Mart (members ads) and Trade Ads. I find the technical topics and the letters from members who have overcome various problems particularly useful. This magazine is free to all AJS & MOC members and is accompanied once a year by the Club Spares Book. This book lists approximately 2000 items for heavyweight twins and singles and lightweights.

Bruce Main-Smith Retail Ltd
BMS produce high quality black and white photocopy sets of Manufacturers original literature that has gone out of print. 182 different motorcycle manufacturers are covered in their extensive list. Instruction Books, Workshop Manuals, Illustrated Parts Books and Annual Sales Catalogues. There are approximately 150 AJS articles, 150 Matchless, four on Amal Carbs and 16 on Burman Gearboxes and Clutches .
Bruce Main-Smith Web Page

Elk Promotions
Elk Promotions produce re-prints of manufacturers spares lists and instruction manuals. 90+ AJS/Matchless Items.
Elk Promotions Web Page

"Matchless & AJS Restoration" by Roy Bacon
The most comprehensive guide to restoration, renovation and the development history of all post-war Matchless and AJS production motorcycles. Invaluable guide to detailing that reveals a model's age and authenticity. Crammed with technical data and invaluable information unavailable from any other single source. Enough of the sales blurb. This is a very useful book without which I would have made a number of blunders during the re-build of my bikes. The appendices are great listing such thing as Engine and Frame Numbers, Model Charts, Model Alterations, Colours, Pistons used, Camshafts used, Sparking Plugs, Carburettor Settings and Spacers, Capacities (petrol and oil tanks), Transmission details, Wheels, Brakes and Tyres and finally Headlamp, Ammeter and Switches
Was published by OSPREY at £19.95. Now out of print. ISBN 0-85045-755-6.

Old Bike Mart Number 1 for Vintage and Classic Classifieds
This is a monthly publication that can only be obtained by subscription. The cost of placing an advert in this paper is very reasonable which leads to people advertising items and particularly spares which might otherwise not be worth advertising. With subscription being approximately £18 for 12 issues you cannot go wrong. Each edition has a "Whats on" section which lists all the Autojumbles for the next couple of months plus the usual trade ads and loads of private ads.
   Old Bike Mart Web Page