How do you replace a transmission modulator on a.

The manual doesn't give specific instructions for replacement of the vacuum modulator. Most are held in by a single bolt and a hold down clamp, simply remove them and pull the modulator out. I would advise you to keep an eye out for the small rod in the center of the modulator, they sometimes get lost or don't make it into the new one which will cause shifting issues.

Exploded diagram of the transmission is attached below