There is one for sale here, the seller might know :cool2:
http://66.102.9.101/translate_c?hl=en&sl=cs&u=http://www.aukro.cz/item527329837_anglicka_moto_prevodovka_a_j_stevens_20_leta.html&prev=/search%3Fq%3Dajs%2BK4/124359%26hl%3Den%26sa%3DG&usg=ALkJrhhGBTU93cCSJw5bQwY8eGfew3cSjA