I tested the X20 Tours when they were a production model, and later bought a set from Callaway PreOwned.
The Callaway 2008 Pocket Reference Guide shows the Project X Rifle Flighted as the stock shaft for the iron.
Also, several X20T iron sets hit the stores with True Temper Dynamic Golf S300 shafts, and an occasional R300.
Not sure how to read the "True Temper" inscriptions on the shaft above the clubhead. Possibly the irons were reshafted at a small golf shop, and the clubfitter failed to put the flex tags on the shafts after the job.
The Uniflex was the stock steel shaft for the standard X20 model. But, Uniflex had a blue tag indicating flex on the shaft. I doubt if anyone who wanted the X20 Tours would have opted for a generic Uniflex shaft.
For the Dynamic Gold family, on an X20 Tour 6 iron, the distance from hosel to the shaft's first step ridge would be about 7 ½" for Stiff, and about 9 ½" for Regular.
If you want to know for sure, follow boggie's advice and contact Callaway.