Unfortunately the online manual site is gone. Also there is more than 1 style of linkage depending on what year and model you have.
When I first got my car the linkage was extremely sloppy and I had no Manual. I felt it was safe to adjust the linkage (under the hood) in 3 places. I started from the Gas Pedal up to the Fire wall.
Next On mine the pivot on the Fire Wall rotates a steel rod; on that steel rod I found a small bolt with a 10mm head and noticed that one of 2 parts it held together had an adjustment slot.
After that the linkages goes up to a complicated Bell Crank where the Cruise Control, Manual Shutoff and other stuff hooks to. I buy passed and left alone all of that as like you I had no manual.
After bypassing as stated above I went down to the Throttle Arm on the Fuel Injection Pump and shortened the length as much as I could and still allowing enough play so that it rested against the Idle Stop (you do not want the idle set with it hanging from the linkage, you want the throttle arm to rest on the idle stop).
Taking the slop out of those 3 areas allowed the Fuel Injection Pump Throttle Arm to move to the fullest of it's range. This gave me better response at the Pedal and more power.

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84 300D, 82 Volvo 244Gl Diesel