What's It For?

I think it's called a shunt line. Probably a bad idea to delete it.

 

If the manufacturer put it on, it's there for a reason. I'd leave it like they built it.

 

That's the line that fills the engine with coolant, it should be a standard 1in water line. The fittings should be, 1in or 3/4in pipe thread by 1in barb. May have to pick up a 45 elbow from plumbing store.

 

That’s all it is, tapered pipe thread nipple. usually brass, found at hardware store.

 

Which fitting?

Hose barbs are everywhere

 

Then go 3/4 bushing to 45 street elbow to 1.5" barb. A million ways to skin this cat.

Have you given McMaster Carr a call? Those guys usually have everything.

Edit: Are you sure it's 1.5" barb? That hose looks more like 3/4" ID.

 

1in fill line is industry standard, I've never seen 1.5 I'd on any truck. A farm supply store will usually have a barb fitting to work. Spray rigs use them so they are normally on stock, atleast every tractor supply and other farm store has them