eos 1d mark III frame counter
On the Mark II's and earlier cameras the frame count was embeded in the EXIF info of each image file. However Canon took this info out of the images for the Mark III and Mark IV. A guy wrote an app to pull the frame count directly out of the Mark IV via a USB connection, but he says it doesn't work for the Mark III ( http://eoscount.com/ ).
I'm pretty positive the only way is to send it to Canon tech support to have them check it, which is what I have done.
Interestingly, you will be able to display the frame count directly on the 1DX's LCD screen.