If it is a T that has hose with quick connects on them you could cut off the quick connects and get a T from NAPA to replace it?
Not the bet solution but a solution possibly
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I would be interested in what a Dealer would say if someone blew a head gasket etc from low coolant if they coudl only top it off and send them away with no ETA on the proper part.
On a truck with 130k miles on it, we say... keep an eye on the coolant level.... here's a little extra to get you by. As I said, this particular truck I had today had a tiny leak. Went from the full line in the degas bottle 2 weeks ago to maybe an inch below it today...~500 miles.
What would an independent shop say if you couldn't get the correct part? The shop is not responsible for the owner's vehicle. If the guy overheats it because he ran it out of coolant knowing he had a leak and drove it till it stopped, that's not our problem.