This sets is designed for the Hotchkiss (based) kits of Bronco (1:35). This is a budget set: if you do not want or need new bogies, this sets will give you just new road wheels, new sprockets and idlers wheels as well as return rollers and a spare road wheel. Finally an early engine hatch is included.
(Assembly) instructions can be found here: http://www.shapeways.com/forum/index.php?t=msg&th=10945 (Please note the grey renderings and 3D 'image' show the latest version of the design, the other renderings have not nescessarily been updated. If you have questions please let us know)