Need help identifying part please, on my 76 280C.

[Tomas7]

On the driver's side underneath the intake manifold, there's a plastic pipe about an inch wide that goes along the side of the motor from the front to the back and then it turns up.
This pipe is leaking oil from the back junction, right unto the front of the trans housing. Is this an oil return line if so, where do I get/find, how do I fix or replace (part Number?) it?

Thanks in advance.