Now I have a good idea of what is out.

When part #6 and the Plunger are in the Fuel Injection Pump Housing in their normal position those elongated holes on each side of the T are there so that the #6 piece can be rotated to adjust the Fuel on that individual Element.
The #6 part with the Plunger is the Element. The only time any of the Elements are supposed to be out of the Fuel Injection Pump is during origional assembly of the Fuel Injection Pump or when the Fuel Injection Pump is being torn down so it can be rebuilt.

When the Fuel Injection Pump is put back tegether it is put on a Calibration stand and the Fuel Quanity for each individual Element is set as well as the Governor so that it delivers the correct amount of Fuel at the correct time.

So the best advice in this case is to either find a good used Fuel Injection Pump or send it to a Fuel Injection Shop and have them put it back together and Calibrate it.
But, in the past Shops did not like to reclabrate a used pump. But, you would not know for sure unless you ask.
One of th 2 choices above is the surest way to get a good results.

I have not had one of these Fuel Injection Pumps apart so I cannot talk you through how to put it back together.
So, the next part is 2nd hand info. Somewhere in our forum one of the Members did pull the same part out.

He said he put it back in and there is some sort of Referance line or raised portion on both the Fuel Injection Pump Housing and one side of #6 (#6 only goes in one way). If you line those up your Fuel quanity is close (that is what he said).

That being said if you get the Plunger back into the wrong place inside of the Fuel Injection Pump Housing; I believe it is possible to damage your Fuel Injection Pump Housing when the Fuel Injection Pump Cam starts pushing it up.

It would be nice if that memeber saw this thread and could give some advice or if you could find his thread and PM him.

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84 300D, 82 Volvo 244Gl Diesel