What is this and should it be connected to something?!

https://imgur.com/a/a1df6QB

 

coolant expansion tank, look at the orange coolant color

 

That is the overflow tank from your coolant reservoir.

If you follow the inboard-upper black hose from the coolant reservoir, it runs along the inside of the front fender and enters the top of the overflow tank just under the ABS unit.

 

There is a coolant flow diagram to make sense in the V8 manual and some have cross connected it at a certain spot

See page 39 for the supercharged version

http://www.jagrepair.com/images/Elec...jm18151280.pdf

See page 22 through 25 for non - supercharged engine

http://www.jagrepair.com/images/Auto...ansmission.pdf

 

Thanks! I hadn't spotted it's connected at the top I was under there trying to get the cooling fan relay/module out and it didn't look to me like it was connected to anything. I stand corrected. (or rather, I lay on my back in the dirt half under the car corrected)