You might not believe what ended up being the fix. After I put back all of the 5/16" bolt clamps on to the lines, I decided to turn the engine over and see if the clamps made a difference. Well yeah, they make a huge difference. The leak is gone. When I was putting the lines back on to the delivery valves, I didn't think the clamps would matter because the engine and pump are vibrating in unison. Now I'm wondering if this has been a wild goose chase and all I had to do in the first place was just torque those clamps down harder than what they were.

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'81 300SD