Does anyone know if the 58-66 coolant overflow tanks are interchangeable to any degree? What about a tank from a galaxie or fairlane of similar year?

It seems they are but parts books show three different surge tanks. I think some of the difference is if the fill cap is centered or off to one side. This of course doesn't affect utility just "original" look.

If I can just get something to fit onto the manifold I'll be more than happy.. I'm tempted to cut the tank away from the thermostat housing and use flex hoses just to get it kicking again

You probably already know but several vendors have new tanks that work, $200 though. Call John Draxler at Thunderbird Ranch, he may have a used one. Also some vendors like Pat Wilson's (N.J.), Tim's Thunderbirds (R.I.) and the Thunderbird company (can't remember the name) in KC sell used parts. They may this.

I would also talk to John about your idea of just using the flex hose. I don't know if these engines are the type but some are susceptible to air locks in the cooling system. This would cause lots of havoc in the engine unless this engine can purge this some how.

Good luck.

I know they have differnt diameter thermostats, So maybe even the flange is not the same or the opening is larger or smaller. Best to check with the venders as Vince said.

I've seen the tank taken off and a regular thermestat housing used, But a radiator with a pressure cap was used. If you have the stock radiator there will be no way to fill it also if the car gets hot you won't have a pressure releif cap and something will surely blow.