I accidentally disconnected the Vacuum Line at the Transmission Modulator and when driving it changed through all forward and reverse gears in a normal manner.
Where I had issue was extremely harsh down shifts.

When you hook up a Gauge to check the Modulator pressure you disconnect the Vacuum Line from the Modulator you drive it at around 30mph and measure the pressure.

Both of what happened in the above cases clearly implies that with no Vacuum you can you should still be able to move forward into First Gear in a normal manner.

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84 300D, 82 Volvo 244Gl Diesel