[bobH]

For whatever it's worth dept..... My military Jeep manuals show a pcv much like described above, maybe even the same. On a MB or GPW, it screws into the intake manifold, directly below the carb. The other side of the valve is plumbed with tubing to the valve chamber, where a road draft tube would be attached on a civilian Jeep. In as much as it is relatively easy to search out and get WWII Jeep parts, maybe a person could get a MB and GPW pcv to check it out.
The manual says that the pcv is closed at idle vacuum.