What is this part called?
 

Hi, I have a 1986 190D non turbo.

Can someone please tell me what the part is called that the fuel prefilter line goes into?

It has 4 hoses going into it. The line that comes from the prefilter attaches to a plastic looking 90 degree elbow piece. It is leaking behind the elbow piece.

Can it be rebuilt?

Thanks.

That's the fuel heater coolant to fuel heat exchanger. Yes parts were likely still are available to rebuild. A lot of people delete them or simply route the fuel line around it

Thank you.