On my 83 SD the vaccuum system is malfunctioning. On occasion, (usu startup), the power brakes, transmission act as if they aren't receiving vaccum (hard shift, hard brake pedal). However, the problem has resolved always in 10 minutes of driving. Sometimes days go by without any problems.
Essentially intermittently no vaccum. Sounds like a bad vaccuum pump?
84 SD 240K
83 SD 130K