Good kit. It even comes w/ an O-ring for the actuation rod (several sizes). The kit I bought on ebay a few years ago (same price or more) didn't have the gasket or O-ring. I used a Viton O-ring from my HF kit. You need an O-ring pick (or similar) to pick the O-ring out of the rod hole. If it leaks, you will get diesel into your crankcase oil. Unlikely the copper seals would start leaking, since they don't degrade. More likely, your hand pump is leaking or the fuel is dripping down from the injectors or tubes.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans