Afternoon guys, we are having some issues with the tranmissions in the CUCVs. We have few that have a really hard shift. We need to rev it to a pretty high RPM before it will shift. Me and my fellow mechanics have adjusted and replaced the vacuum control on the side of the injection pump. We have replaced all dry rotten vacuum hoses from the vacuum pump to the control on injector pump down to the Mod valve on the transmission. We've even replaced the mod valve. No matter what we've done, it is still shifting hard. My question is,l is there a way to test the Air emission pump on top at the back of the engine? I have searched the 10, 20 and 34 manuals for something about the vacuum pressures or the amout needed to properly shift gears. It explains how to change it but no way to test it. I am really hoping that we don't have to have it rebuilt. I have read about the trans oil pressures but nothing about vacuum pressures. I am looking for some insight about this matter.