If you have the seat box and tracks out and upside down undo the motor flex cable from the track gear. In the square drive hole insert the square tang of a round file and turn to move the seat along the tracks to line up the access holes for the bolts.
I turned the round file with a reversing variable speed drill.
I hope I understood your problem.

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1984 300SD turbo 126
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God made me an atheist and who am I to question His wisdom