I see in the 1969 engine assembly manual that a PI engine of that era used a passenger side hose similar to the CJ one but shorter. The check valve is located at the front of the head on a PI and at the rear on a CJ. So, if that hose is too short to be a CJ style setup, it could be PI.
I don't have any 1968 manuals to look at, but the engine assembly manual shows all the different Thermactor configurations.