Hewland Engineering is the manufacturer of virtually all gearboxes used in Formula Ford racing these days.

Gearbox manuals are available below, but can also be obtained from the website for Hewland direct:

http://www.hewland.com/ 

Hewland LD200 Manual:

 Hewland LD200 Compressed File 

Hewland Mk8 / Mk 9 Manual:

 Hewland Mk8/9 Adobe Acrobat