This is the release arm dust boot used on many rear wheel drive Ford gearboxes, such as
Type 3 - 4 speed on Cortina, Sierra, Capris and Escorts
Type E "Rocket" - 4 speed on Cortinas, Sierras, Capris and Escorts
Type F - 4 speed rod boxes on Capris
Type 9 - 5 speed on Cortinas, Sierras, Capris, and Granadas
Type 5 - 4 speed but only 2.8 version - NOT Essex 3 litre versions - Capris and Granadas
etc.