Hello Themoneta!
Welcome to the Canon Forums!
If you would like to find the shutter count of your EOS 5D Mark III, you will need to send your camera in to be evaluated with a request for shutter count included. Our technicians will send you an estimate to let you know the cost, if there is any, before anything is done. The shutter count will be included in the evaluation upon request. To send in your camera for evaluation please go HERE
Thanks!