Stacks of cash and a GPS jammer device were seized following a search of a car on a major highway.
Officers from the Central Motorway Police Group - which cover Staffordshire and the West Midlands - said the bundle of notes and an electrical device were found inside a vehicle traveling on the M6.
Two men were inside the engine at the time of the Thursday April 30 shutdown, a force spokesman said.
It is not known if they have been arrested but cops have been contacted for further comment.
A spokesperson added: "If you are using our network to commit a crime we will stop and deal with you. Just like two guys we pulled over on the M6. A large amount of cash and a jamming device car recovered.
What is a GPS Jamming Device?
A GPS jammer is a type of signal jammer that effectively blocks the location of the vehicle from being visible to an external tracker.
GPS jammers are relatively small devices that can be plugged into a lighter port on any vehicle to emit radio signals to interfere with weak GPS signals over a radius of between 5 and 10 meters.