For me, the hardest part of this job was removing the fan bolts. You need a 6 point 10mm box end wrench with the nose ground down a bit to take them off. One of mine rounded off just trying to use a regular wrench.

I did not need to take the housing off, just the pump itself. Haynes has a fairly good account of this job as well.

dd

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car