Anyone know where I can find one for a 1970 Ninety Eight 455? I've tried Rockauto and GM obsolete. Also have a search on EBay. Other years/models that would work? Right now the overflow hose just drains on the ground. Thanks,
Tom

 

Try ebay

 

Closed cooling systems weren't offered in 1970. Option was first available on 1971 Toronados, then on the 1972 B/C cars.

You have two options. An aftermarket universal kit, or adapt one from a later car. You should have plenty of room for it underhood.

Now. Next ?? Why do you think you need one? If the car is puking out the overflow tube with coolant at normal level in the radiator, you have a problem an overflow tank isn't going to solve. Either you have a bad pressure cap, a thermostat issue, or a possible blown head gasket.

If you're trying to keep the radiator full to the filler neck, it is going to blow coolant out the overflow pipe until it achieves its normal level, which should be about 3" below the filler neck- the tank should have Fill Cold embossed into it. As coolant heats up, it expands. With the proper level in radiator, it will expand until the core is completely covered with coolant and proper heat transfer will then take place. With too much, it is going to expand out the overflow.