Try a dealer, that looks just like a 603 pump. You will need o rings that run about $.50 each and some crush washers that run about the same. You can do all 6 or just that one. Make sure you use a good torque wrench and follow the torque specs. I would try to find 606 specific torque specs.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200