[QUOTE=Clemson88;3604443]When you let off the accelerator the vac to the tranny increased.

The transmission was disconnected from the VAV and was instead hooked into the Mityvac. So there could not have been any effect on the tranny when I let off the accelerator as there was no physical connection.

There was no vac applied to the transmission on upshifts because the plastic line to the vac modulator was open. I closed it and pumped it up when I got ready to downshift and it downshifted without a clunk.

However to get back to the original poster's thread, I think he needs to make sure the pump provides about 12 inches or so of vac and that the vac modulator on the tranny is connected by the plastic line and does not leak.

If he does not have 12 inches, he removes the dome from the VAV and adjusts the screw ever so slightly. And he may also need to check the gap for the VAV. Something like setting points.