There is provided transmission module (10) for a tractor which is selectively configurable between a CVT arrangement and a multi-ratio powershift transmission arrangement. The module comprises an epicyclic unit (13) in which a first gear element of the epicyclic is driven mechanically from the input shaft (11) and a second gear element of the epicyclic acts as an output of the transmission module. By simply connecting either a CVT unit (24) or a pair of clutches (80) between the input shaft and a third gear element the module (10) can be converted to the desired transmission arrangement. This delivers benefits in a factory for example whereby a large proportion of the assembly can be completed before tailoring the transmission to a customers requirements, thus reducing lead times on delivery.